50+0.4x=0.6x50+0.4x-0.4x=0.6x-0.4x50=0.2xx=50÷0.2x=250
这样
50+0.4x=0.6x(0.6-0.4)X= 500.2x=50X=50/0.2=25o
0.6x-0.4x=500.2x=50x=500/2x=250