< <<
13-9= 15-8= 12-5= 7+6= 12-9=
17-2= 30+4= 56-6= 14-6= 78-8=
65-60= 45-5+8= 9+5-7= 17-8-3=
7227 15-77 10个十100
7+3033 13-86 75-706