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=
25+6=
18-9=
43+50=
45-7=
25-6=
56+6=
22+5=
45+7=
60+26=
25+5=
9+15=
33-9=
6+94=
66+3=
61-5=
30-3=
62- (37+3)=
56-8+2=
56-(58-50)=
16+7+4=
40+(17+6)=
88-88+89=
24-7+8=
66-8+7=
33-(14-9)=
5元8角-2元=
1元-3角=
6元-5元5角=
13-5 12-6 16-8 16-9 14-5 15-6
15-9 13-8 14-715-8 18-9 12-4
①正方形的周长和它的边长②一个圆的面积与它的半径③书的总页数一定,已读的页数和未读的页数④《百科全书》的单价一定,购买的总价和数量