(2/5+1/3-7/15)*15简便算
问题描述：
(2/5+1/3-7/15)*15
简便算
答
(2/5+1/3-7/15)*15
=2/5*15+1/3*15-7/15*15
=6+5-7
=4
答
(2/5+1/3-7/15)*15
=2*3+1*5-7 乘入15
=6+5-7
=11-7
=4