(20-x)除以(30-x)=3怎么计算

问题描述:

(20-x)除以(30-x)=3怎么计算

(20-x)除以(30-x)=3
(20-x)=3(30-x)
20-x=90-3x
-x+3x=90-20
2x=70
x=35