横行相加得,竖行相加得 。
2+ =
5+2-=4
8+68+9 17-75+5 10-36
1220 3+1+28-1-3 89-8
□○□○□=□(个)
7-5+3= 8+2-6= 10-4+3=
5+2+3= 6+3-7= 9-5+2=