20以内三连减口算练习题(144).docx

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1、20-4-9=16-6-6=20-7-8二15-2-9=18-8-4=15-6-7=16-13-3 =19-3- 12 =15-8-2=17 - 1 - 16=19 - 12 - 1=14-4-2 =20-7-11 =6-2-4=19-4-15 =10-1-1 =20-5-3 =20-2-4=8-2-1=14-9-2 =11-3-1=20-8- 12=15-3-6=7-2-1=16-3-9=10-4-3 =20-1- 10=12-1-6=16-1-2 =20 - 13 - 7=8-2-2=13-3-10=7-2-4=20-7-9=17-1-9=5-3-2=16-6- 10=7-1-6=19-6

2、-6=13-2-8=16 - 10 - 6=17 -11-4=6-4-1=17 - 13 - 1=20-4-1=16-3-12 =17-3-9=10-5-4=19-2- 17=19-5-8=17-3-7=17-3-13 =17 - 10 - 4=13-9-3 =19-3- 16=13 -10 - 2=18-1-9=20-3-10=6-3-1=19-9-3 =20-7-6=19 - 12 - 2二13-8-5=20-2-3 =20 -13 - 3=12-4-7=18-4-12 =18-5- 10=10-2-7=11-1-7=20 - 12 - 6二14-9-5 =12-3-9=14-1-9=11

3、-5-2 =17-11-1 =17-3-3 =12-2-7=7-5-1=20-9-6=19-1- 13 二15-9-3 =20-1- 14=20-6-2 =17-10-3 =11-1-9=13-2-2 =8-4-1=5-1-4=3-1-1=20-8-8二18-10-3 =19 - 13 - 6=14 - 12 - 1=17-1-7=15-3-9=17-8-8=7-3-3=17-2-1=20-4-7=13-4-4=16-6-7=12 - 1 - 11=8-4-4=9-4-4=18-3-9=20 - 10 - 8=18-3- 10=9-4-2=15-4-1=19-15-2 =19-8-7=19-9

4、-4=15-4-3 =15-8-6=12-1-7=10-1-9=7-4-2=18-5-5=16-3- 10=10-8-2 =13-3-4=12-4-2 =15-4-8=18 - 3 - 14= 13-4-8=16-2- 10=19-6-4=20 - 12 - 5=18 - 5 - 11=15-1- 10=17 - 5 - 11=11-2-2=12-6-4=14-5-8=12-7-4=18-4-8=7-2-3=15-3-3 =19-2-10=18-9-9=16-6-8=19-7-7=9-5-2=16-8-2=10-7-2 =11-4-3 =20 - 16 - 4=18-7-9=17-5-1=15

5、-5-9=17-8-1=16-9-3=20 - 12 - 2 =15-2-4=18 - 14 - 3=20 - 14 - 1=19-6-9=19 - 11 - 1=19-3-4= 12-5-2 =11-9-1=20 - 14 - 5= 15-10-4=19-1-8=18-7-1=16-5-11= 14-5-2 =6-4-2= 16-3-4=11-2-5=9-2-1=11-2-6=9-1-5= 17-7-9=15-2-2 =19 - 12 - 3二 20-4-16=19-5-9=17 - 11 - 6二9-2-4=18-3-4=14-6-1 =20-5-2 =17 - 15 - 1=20 -18

6、 - 2=11-2-8=12-3-7=15-6-5=12-5-1 =20-1- 17=10-5-3 =16-4-9=16 - 14 - 1=20-1-9=10-5-5 =20-3-4=13-1-4=10-1-3 =10-3-1 =14-11-3 =9-7-1=19-6-11 =19-4-6=17-9-7=18-1- 17=16-1-11 =17-2-15 =16-2-13 =9-6-1=20 - 10 - 4=18 - 15 - 3 =11-1-4=15-7-5 =16 - 12 - 1=12-6-5=18-7-2 =20-8-6=13-2-6=13-2-3 =17-1-8=12-2-5 =1

7、9-8-9=17-2-3 =6-2-3=3-1-2=16-2-6=19-3-1 =14-9-4=18-8-6=19-1- 16=19-4-11= 14-8-6=7-2-2=12-2-2 =11-2-3 =20 - 5 - 12= 18 - 13 - 5 = 16-1- 13= 19-2-13 =19 - 12 - 5= 19-4- 14=12-10-2 =16-4-10=14-8-4=16-9-1=13-6-7=20-2- 17= 18-16-2 =错误率,18-3-12= 16-1-8= 20-7-4=17-8-7=13-7-3 =20-5- 14=13-8-4=15-10-3=8-4-2=

8、11-2-9=15 - 3 - 12= 17-4-13 =18 - 12 - 4= 19-5-3 =20 - 12 - 8=19 - 13 - 1= 11-1-1=14-6-2 =13-6-1=18-8-8=15-5-4=20-6-6=17-2-4=20-4-12 =16-8-3 =17-5-7=11-5-4=14-6-6=15-4-6=12-5-4=20-7-12 =20-1-11 =14 - 11 - 2 二9-1-8=20 - 13 - 4=18-5-9=17-7 - 10=19-4- 10=16-2- 12=11-1-2 =20-3-5 =11-1-3 =15-8-4=17-12-2

9、=14-7-2 =13-5-6=14-1-7=6-3-3=15-6-4=12-9-1 =11-4-6=19-1- 14=12-8-3 =4-3-1=17-14-3 =12-3-5=20-1-7=13-11-2 =9-2-2=17-2-5 =17 - 14 - 1=14-3-1=7-4-1=20-1-4=14-6-3 =17-6-11 =5-2-1二18 - 14 - 4=19 - 3 - 11=19 - 3 - 15 =14-5-1=18-3-1=14-3-4=16-7-2 =11-9-2 =16-1- 10=9-1-4=7-1-2=6-2-2=20-3- 12 =9-2-3=19-8-1=1

10、6-8-4=19-7-9=20-9-11 =15 - 1 - 12 =12-1-9=20-4-13 =14-2-3 =19-7-12 =19-14-3 =17-2- 12=13-3-8=20-9-8=15-1-8=17 - 12 - 1=17-3-6=18-2-6=18-11-3 =20-2- 14=14-3-9=15-2-1=15-7-1=18-4-4=17-7-3 =4-2-2=15-2-11=19-4-3 =12-4-8=18-9-2 =8-1-1=19-2-15 =17-8-3 =17-2-11=13-3-5 =20-6-7=19-11-7=16 - 1 - 12 =18 - 14 -

11、 1=17-1- 12 =14-2- 10=8-6-1=20-3-13 =18-14-2 =13-2-9=12-8-2 =17-11-3 =16-5- 10=11-2-1=16-1-7=17-5- 10=11-6-5=9-1-6=16-1-6=15-6-6=15-6-8=16 -10 - 4=15-11-4=5-1-2=17-5-4=20-4-5=18-7- 10=19 - 12 - 7=20-12- 3 =14-4-6=19-1-6=18 - 10 - 1二20-6-13 =13-1-2 =10-1-2 =9-1-3=19-1-3 =13-4-2 =19 -11 - 8=12-1-3 =20

12、-5-7=13-3-7=15 - 13 - 1=9-3-2=2-1-1=14-7-1 =18-8-3 =19-7-8=9-3-1二14-5-7=18-6-10=20-4-4=15-5-3 =20-14-2 =12-2-9=18-4-2 =20-7-3 =16-3- 13 =15-4-2 =20-9-1 =19-7-11 =20-3-7=14-6-5 =14-5-4=18-2-1 =10-4-4=17-3- 12 =14-1-13 =17 - 10 - 7=16-11-1 =15-3- 10=11-3-4=17-5-8=16-8-1 =19 - 10 - 4=12-5-3 =9-3-5二17-3

13、-11 =18 - 5 - 12 =11-4-2 =18 - 11 - 2=19-2-3 =14-4-5 =14-1-8=19-4-4=19-8-4=18-7-8=17-10-5 =8-1-4=12-9-3 =11-1-6=15-8-3 =15-7-3 =10-6-2 =16-12-2 =20 - 10 - 7=15-1-7=14 - 13 - 1=20 - 12 - 7=16-5-1=19-14-5 =16-1- 14=20-1-8=17-2- 10=18 - 12 - 5=20-1- 19=20-6-8=17-6-1=19-8-2 =13-3-1=10-2-4=20 - 10 - 6=17

14、-13-2 =20-3-2 =18 - 10 - 4=16-4-4=20-15-1=14-3-7=20-2-2 =20 - 13 - 5=16-2-2 =20-11-5 =17-5-5 =18-16-1 =18 - 10 - 2=12-2-1 =11-5-3 =8-5-3=15-6-2=13-1-5=11-4-1 =19 - 3 - 14=15-9-5 =14 - 12 - 2=18 - 1 - 11 =12-2-6=17-7-6=20-7-2 =8-5-2=18-1-7=9-3-4=8-6-2=18-6-9=17-1-3 =15-7-2 =18 - 10 - 8=13-1- 12=19 -

15、10 - 5=14-4-9=19-9-6=18-2-11=19 - 16 - 1=5-2-2=4-2-1=13 - 1 - 10=10-4-2 =9-1-7=8-2-6=20-2-12 =15-2-12 =13-1-3 =14-2-4=20-9-9=12-7-2 =7-3-4=10-3-7=17-2-6=19 - 5 - 13 =14-1-11 =14-5-5 =19 - 15 - 1二 17-4-4=18-3-15 =20-3- 14=16-2-11=18-6-7=20-7-1 =19 - 17 - 1= 15-14-1 =9-3-6=15 - 10 - 2=15 -10 - 5=10-2-

16、6=20-1-15=17-9-3 =17-4-2=18 - 12 - 1=8-7-1=13-9-4=13-1-8=18-8-5=13-5-5=20-3-9=15-1-9=17-8-2 =13-3-9=17-1-1 =19 - 14 - 1=19-1-2=20-5-6=17-1-5 =16-6-1=18-1-5 =20 - 19 - 1=17-4-6=11-5-6=18-3-3二19-2-2 =8-1-6=19 -11-4=19 - 14 - 4 二13-6-2 =13-7-1 =18-5-1=15-1-5 =20-2-7=18-1-8=20-2-15 =11-4-4=8-3-2=6-1-5=1

17、8-8-1=8-3-3=18-2-15 =16-2-9=10-3-5=13-3-3 =20-6-11=12-1-4=17-6-2二16 -13 - 2=17-11-2 =19-2-1=16-3-2 =16-3-8=20-14-3 =16-2-8=11-3-3 =19-6-12 =18-5-7=20 - 17 - 3二17-4-3 =16-2- 14=10-1-7=18-1-2 =17 - 1 - 10=18-1- 10=20-4-3 =19 - 3 - 13 =14-1-5 =14-7-3 =18-2-2 =18-6-6=15-13-2 =19-5-6=20-5-1 =20-5-4=17-2-

18、2=16-4-8=18-2-4=11-4-5 =19-7-3 =20-1-2=17-15-2 =19-3-3 =18-4-9=11-3-2 =11-4-7=12-6-1=11 - 1 - 10=18 - 15 - 2=13 - 1 - 11=16-1-1=15-1-11=20-11-2 =19-4-13 =17-5-9=17-8-9=14-10-3 =19-3-9=17 - 1 - 15 =5-3-1=15-5-5 =18-5-8=9-1-1=19-4-12 =18 - 12 - 2=13-6-3=4-1-1=13-2-7=12-5-7=17-8-4=9-5-3=13-4-3 =20 - 16

19、 - 1=17-3-2 =15-9-4=19 -15-4=8-2-3=17-2-7=16-6-3 =20 - 10 - 9二16-14-2=14-3-6=18 - 1 - 16=20-6 - 10=13-8-3=16-5-3 =19-1-11=15-8-5 =18-3-5 =17 - 13 - 3=20-3-6=15-3-5 =16-3-7=16-8-5=18-6-11=10-6-1=20 - 12 - 4=10-8-1=20-5- 10=18-3-2 =16-4-1=13-3-6=18-11-5 =19-8-8=15-1-3 =16-1-3 =20-1-1=10-2-5 =17-7-2 =2

20、0-8- 10=20-15-5 =9-2-7=19-5-2=6-1-1=14-4-1=14-1-1=19-1- 12=14-3-11 =10-7-3 =20-1- 16=19 -11 - 2=18-4- 14=18-3-8=10-2-3 =10-1-5 =17-6-6=20-2- 10=20-2-6=20-2-9=9-6-2=17-7-5 =20-2-13 =20-10-3 =20-2-11=17-5-2=16-2-4=20 - 17 - 1=20-7-5 =13-5-4=16 - 10 - 1=19-2-6=20 - 1 - 13 =17-1-2=20-4-6=13-4-1=14-7-4=8

21、-5-1=19-1-9=4-1-2=14-4- 10=18-13-2 =10-3-4=20 - 14 - 4=13-7-2 =7-2-5=18-4- 10=17-1-6=20-4-2 =18-6-12 =15-3-2 =15-7-7=17-10-2 =20-8-1二19 - 15 - 3二13-5-3 =20-15-2 =10-4-1=14-1-12 =11-1-8=15-1-4=15-4-4=15-6-1=14-3-2 =17-6-4=19 - 13 - 3=15-5-6=16-2-1=13-9-2 =18-9-7=18 -10 - 5=13 - 10 - 3=6-1-2=13-2-1=11

22、-5-1=16-4-5 =10-6-3 =15-2-6=14-3-8=18-1-4=20-6-3 =20-8-5 =12-4-5 =20-7-7=15-4-7 =15-7-6=18-6-2 =16-9-2 =8-2-4=20-11-7=15-9-1=17 - 13 - 4=18-2- 14=16-7-4=16-6-9=13-9-1=15-2-5 =6-3-2=15-11-1 =19 - 1 - 17=12-1-8=15-5-2=13 - 11 - 1=16-6-4=15-7-8=18-4-7=16-4-2 =17-3- 14=14-7-7=14-8-1 =20-2-1 =19-4-7=18-5

23、-4=13-1-7=17-8-6=18 - 13 - 3=18-4-13 =16-5-8=14-9-3 =18-8-7=9-7-2=18 - 13 - 4=20 - 13 - 1=12-8-1=16-7-5 =13-6-5 =18-6-1=11-6-2 =12-2-8=20-16-3 =16-5-4=15-8-7=20-5- 13 =20-11-1 =10-1-6=17-6-8=20-5-15 =12-7-3 =11-8-1=19 -13-4=12-8-4=10-3-2 =6-5-1=15 - 11 - 3二17-2- 14=17 - 16 - 1=13-2- 10=18-9-6=20 - 1

24、8 - 1= 20-11- 3 =18-7-11 =19 - 5 - 14= 16-4-12 =19 - 10 - 9二13-1-9=13-1-6=20-6-1=17-5-6=19-5-11 =18-2-3 =9-8-1二20-3-1=14-1-4=16-6 - 10=7-1-6=19-6-6=13-2-8=16 - 10 - 6=17-11-4=6-4-1=17 - 13 - 1=20-4-1=16-3-12 =11-6-1=20-7-13 =10-6-4=17 - 12 - 3二12-3-2 =14-1-3 =20-4-9=16-6-6=20-7-8二15-2-9=18-8-4=15-6-

25、7=16 - 13 - 3 =19 - 3 -12=15-8-2 =17 - 1 - 16=19 - 12 - 1=14-4-2 =17-4-5 =15-3-7=15-9-6=16-4-6=17-4-9=8-2-1=14-9-2=11-3-1=20-8-12 =15-3-6=7-2-1=16-3-9=10-4-3 =20-1- 10=12-1-6=16-1-2 =20 - 13 - 7=10-5-4=19-2- 17=19-5-8=17-3-7=17-3-13 =17 - 10 - 4=14-2-2 = 14-4-7=17-2-2 = 16-4-8=18-2-4=11-4-5 =19-7-3

26、=20-1-2 =17-15-2 =19-3-3 =18-4-9=11-3-2=6-2-4=19-4-15 =10-1-1=20-5-3 =20-2-4=8-1-2=18-8-1=8-3-3=18-2-15 =16-2-9=10-3-5 =13-3-3 =20-6-11=12-1-4=17-6-2 =16 - 13 - 2=17-11-2 =19-2-1 =7-2-4=20-7-9=17-1-9=5-3-2=17-4-8=18-5-7=20 - 17 - 3二17-4-3 =16-2- 14=10-1-7=18-1-2 =17-1- 10=18 - 1 - 10=20-4-3 =19-3-13

27、 =14-1-5 =14-7-3 =12-6-1=11-1- 10=18 -15 - 2=13 - 1 - 11 =16-1-1=15 -1 - 11=19-11-3 =9-1-2=5-1-3=10-1-4=20-4-8=12-2-3 =9-6-3=17-9-2 =13-1-1=15 -12 - 2=19-5-5 =19-1-15 =16-3-8=20-14-3 =16-2-8=11-3-3 =19-6 - 12=11-8-3 =12-3-4=7-1-3=14-6-7=18 -11-4=19 - 12 - 6=20-4- 14=9-4-5=10-4-5 =19 - 1 - 10=16-7-9=

28、20-3-15 =16-9-4=15-13-2=19-5-6=20-5-1二20-5-4=18-2-5=20-6-9=12-3-6=11-7-4=15-5-7=16-5-6=11-7-3 =12-4-4=16-2-5=13-6-4=7-5-2=18 - 1 - 14=19-14-2 =13-6-6=20-5-9=17-2-13 =17-2-8=20-1-3 =18-2-7=13-5-1 =7-1-1=16-3-11 =17-6-9=18-1- 12=18-4-1 =12-6-2 =16-3-1 =17-3-1 =19-5- 10=12-11-1=19-6-7=15 - 12 - 3二6-2-1

29、=14-2-5 =14-5-9 =20-2- 18=18-6-4=20 - 10 - 1=19-3-2 =19-2- 14=14-2-6=14-4-8=14-4-4=13-7-5 =17-8-5 =18-2-9=16-10-3 =20-8-9=18 - 10 - 6=7-1-5=15 - 3 - 11=11-1-5 =15-2- 10=12-3-1=12-4-3 =18 - 11 - 6=11-2-4=17-3-8=19-6-1=18 - 11 - 1=9-4-3=14-8-5 =11-3-6=9-4-1=12-3-3 =10-1-8=14-7-6=16 -13 -1=7-3-1=17-5-3

30、 =19-1-7=19-16-3 =17-3-5=12-4-1=19-7-2 =20-8-11=17-9-8=19-7- 10=18-6-3=14-5-3 =7-4-3=19-6-8=20-6 - 14=11-8-2 =13-2-4=3-2-1=16-3-6=20 - 11 - 9= 11-3-5 =19-2-7=6-1-4=17-4-11=12-1- 10=19-6-3 =12-7-1=20-5- 11=11-7-2 =11-7-1=18 - 10 - 7= 14-9-1=19-8-6=16-7-7=11-3-8=17-9-5 =16 - 12 - 4=16-11-3 =16-6-5 =10

31、-2-2 =19-2-5 =15-1-13 =20 - 13 - 2=11-6-4=18-1-13 =16-5-5=14-8-2=19-2-9=12-5-6=10-5-2 =14-2-8=20-6-12 =20-9-2 =15 - 12 - 1=17-4-1 =12-2- 10=19-8-11 =19-3-5 =14-6-8=20-15-3 =19-5-1 =17-6-5 =19-5-4=15-7-4=16-7-8=20-1-6=17-6 - 10=20-11-8=17-3-4=15-6-9=15-1-6=17-7-1=19-5-7=18-5-3 =12-6-6=18 - 12 - 3 =17

32、-6-7=16-4-7=20 - 13 - 6=20-1- 18=16-3-5 =8-3-5=20 - 16 - 2 =13-2-5 =18-6-8=10-2-8=15-4-11=错误率,PH10-4-6=11-6-3 =20-9-5=19-4-8=16-1-15 =19 - 18 - 1=14-3-5 =15-3-8=18-9-3 =18-5-6=12-1-1=19-6-2 =20 - 14 - 6=17 - 5 - 12=20-9-7=18-3-7=19-3-6=17-1- 13 =12-3-4=7-1-3=14-6-7=18-11-4-19 - 12 - 6二20-4- 14=9-4-5

33、=10-4-5=19-1- 10=16-7-9=20-3-15 =16-9-4=19-3- 10=15 - 12 - 3二6-2-1=14-2-5 =14-5-9=20-2- 18=20-6-9=12-3-6=11-7-4=15-5-7=16-5-6=11-7-3 =12-4-4=16-2-5 =13-6-4=7-5-2=18 - 1 - 14= 19-14-2 =20 - 3 - 11= 19-7-1=7-1-5=15 - 3 - 11= 11-1-5 =15-2- 10=5-1-3=10-1-4=20-4-8=12-2-3 =9-6-3=17-9-2 =13-1-1=15 -12 - 2=

34、19-5-5 =19 - 1 - 15 =17-9-6=13-6-6=20-5-9=17-2-13 =17-2-8=20-1-3 =18-2-7=18-4-11 =8-1-5=15 - 5 - 10=15-6-3 =19-1-5 =15-2-13=20-8-4=19 - 10 - 6=20-5-8=12-1-5 =19-8 - 10=19 -13 - 2=15-5-8=19-2-11=20-6-4=8-1-7=17-7-7=18 - 12 - 6=17-7-4=19-10-3 =20 -11 - 6=13-4-6=13-5-8=8-3-1=8-2-5=20-4-15 =20 - 10 - 5

35、=16 -11-4=15-2-7=19 - 1 - 18=16 - 15 - 1 二16-1-4=11-5-5 =14-4-3二19 - 11 - 5=15-2-3 =14-3- 10=20 -10 - 2=14-6-4=11-3-7=19-7-4=7-1-4=18-2-12 =18-8-9=20-9-3 =20-2 - 16=13-3-2=16 - 10 - 2=19-4-9=19-4-2=9-2-6=20-5-5 =13-2-11=15-3-4=19-9-1=5-2-3=16-8-6=19-7-5 =18-9-4=13-4-9=20-3-8=8-4-3=18 - 13 - 1=20-3-

36、17=15-1-1 =18 - 17 - 1=18-2- 10=17 - 12 - 5二17-7-8=16-5-7=20 - 10 - 10=20-7 - 10=10-7-1=19-10-2 =16-9-7二15-1-2 =12-1-2 =10-9-1=16-2-3 =20-4- 10=14 - 10 - 4=14 - 10 - 1=14-2-7=15-10-1 =16-5-9=16-7-1=14-2-9=9-5-4=13-5-2 =错误率,PH18-2-13 =9-2-5=13-5-7=18 - 3 - 11=8-1-3=20-6-5 =10-2-1=13-7-4=17-11-5 =16-9

37、-6=17-4-12 =19-9- 10=16-8-8=5-1-1=19-8-3 =16-10-5 =20-3- 16=13-4-7=18-5-2=15-2-8=12-7-5 =16-3-3=19-8-5 =17-4- 10=14 - 10 - 2=20-2-5=16-11-5=18-7-6=8-3-4=19 - 10 - 8=18-7-5 =14-7-5二18-4-6=17 - 10 - 6二17-1-11 =12 - 10 - 1=20-8-2 =18-7-3 =18-2-8=12-3-8=18-1-3 =20-8-7=20 - 12 - 1=19-4-1=16-5-2 =16-1-5 =

38、14-1-2 =13-8-1=17-9-4=18-7-7=18-8- 10=15-4-9=16-7-6=19-2-4=11-10-1=13-10-1=19-2-16=20-4-11 =13-4-5 =12-2-4=12-5-5 =19 - 10 - 1二19-1-1=13-7-6=18-9-5 =20-9 - 10=20-2-8=6-1-3=20-8-3 =20 -11-4=18-3-6=19-9-7=18-1-15 =12-6-3 =17-1-4=10-5-1=20-1-12 =13 - 12 - 1 =15 - 1 - 14=3-1-1=20-8-8=18-10-3 =19 -13 - 6

39、二14 - 12 - 1二17-1-7=15-3-9=17-8-8=7-3-3=17-2-1=7-6-1=13-8-2 =18-5-13 =16-6-2 =18-11-7=16-1-9=13-9-3 =19 - 3 - 16=13 -10 - 2=18-1-9=20-3-10=6-3-1=19-9-3 =20-7-6=19 - 12 - 2 =13-8-5=20-2-3 =20 - 13 - 3二17 - 10 - 1=4-1-3=15-3-1 =18-4-5 =20-1-5 =14-9-5 =12-3-9=14-1-9=11-5-2 =17 - 11 - 1=17-3-3 =12-2-7=7

40、-5-1二20-9-6=19-1- 13 =15-9-3 =20-1- 14=13-4-4=16-6-7=12-1-11=8-4-4=9-4-4=18-3-9=15-8-1=19 - 12 - 4=19-7-7=9-5-2=16-8-2 =10-7-2 =11-4-3 =20 -16 - 4=18-7-9=17-5-1 =15-5-9=17-8-1=18-4-12=18 - 5 - 10=10-2-7=11-1-7=20 - 12 - 6=19-4-5 =20 - 10 - 8=18 - 3 - 10=9-4-2=15-4-1二19 - 15 - 2=19-8-7=19-9-4=15-4-3 =15-8-6=12-1-7=10-1-9=7-4-2=11-1-9=13-2-2 =8-4-1二5-1-4=14 - 11 - 1=18 - 3