70(Y+60)=X 100(Y-30)=X 怎么解

问题描述:

70(Y+60)=X 100(Y-30)=X 怎么解
70(Y+60)=X
100(Y-30)=X

70(Y+60)=100(y-30)
7(y+60)=10(y-30)
7y+420=10y-300
7y-10y=-300-420
-3y=-720
y=240
x=21000