40乘以0.2x减0.25x=7怎么算?
问题描述：
40乘以0.2x减0.25x=7怎么算?
答
40*0.2x-0.25x=7
8x-0.25x=7
7.75x=7
31/4x=7
x=7*4/31
x=28/31