20+31= 87-5= 7+62= 37-6=
96-3= 60+10= 43+5= 68-8=
54+20= 49-40= 72-40= 70+9=
16-9= 14-7= 15-6= 17-8=
13-7= 12-5= 14-8= 18-9=
17-8= 12-7= 15-8= 13-4=
8+4-9= 9+9-8= 19-10+8= 16-8-6=
79-9= 99-90= 60+7= 14-7+8=
85+7=□
68 78
76﹣3 73
30 40﹣7
37﹣9 37+9
69﹣30 29
8元9角 9元
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