{X-Y=630 {X(1+20%)+Y(1-10%)=(X+Y)(1+12%) 怎么解

题目

{X-Y=630 {X(1+20%)+Y(1-10%)=(X+Y)(1+12%) 怎么解

答案

1.2x+0.9y=1.12x+1.12y
0.08x=0.22y
x=2.75y
代入x-y=630
2.75y-y=630
1.75y=630
y=360
y=2.75y=990