20以内三连减口算练习题(3).docx

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