由已知得x-y=-3xy,代入得（2x+3xy-2y）/（x-y-2xy）= 0.6
3/51/x-1/y=3>>>>y-x=3xy故2x+3xy-2y＝x-y=-3xy x-y-2xy=-5xy故（2x+3xy-2y）/（x-y-2xy）＝3/5
