(0.4y+0.9)/0.5-(0.3+0.2y)/0.3=1方程两边同时乘以1.5.得3（0.4y+0.9)-5(0.3+0.2y)=1.51.2y+2.7-(1.5+y)=1.51.2y+2.7-1.5-y=1.50.2y=1.5+1.5-2.7=0.3y=0.3/0.2=3/2另外发并点击我的头像向我求助,请谅解,,你的采纳是...