的分子加上8，要使这个分数的大小不变，分母应该加上________．直接写出得数．
| 870-780= | 40×13= | 105÷3= | 60÷12= |
| 88÷22= | 12×4÷12×4= | 25×189×0= | 800÷80= |
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=
=
=
=
=
=
=笔算．
| 308×75= | 267×45= | 470×80= | 125×40= |
如图中三角形的周长可能是____厘米．解方程．
 X= | X：45= | x+ x= |  x÷ =18． |
| 870-780= | 40×13= | 105÷3= | 60÷12= |
| 88÷22= | 12×4÷12×4= | 25×189×0= | 800÷80= |
| 308×75= | 267×45= | 470×80= | 125×40= |
| X= | X：45= | x+x= | x÷=18． |