简便计算:13/15*2/9+7/15*13/9

问题描述:

简便计算:13/15*2/9+7/15*13/9

13/15*2/9+7/15*13/9
=13/15*2/9+13/15*7/9
=13/15*(2/9+7/9)
=13/15