X - 1/4X =4/5X +1/4X -30

问题描述:

X - 1/4X =4/5X +1/4X -30

X - 1/4X =4/5X +1/4X -30
X - 1/2X =4/5X -30
1/2X =4/5X -30
3/10X=30
X=100