x分之1-y分之1=3
(y-x)/xy=3
y-x=3xy
(2x+3xy-2y)/(x-2xy-y)
=[3xy-2（y-x)]/[-2xy-（y-x）]
=（3xy-6xy）/(-2xy-3xy)
=(-3xy)/(-5xy)
=3/5
如果本题有什么不明白可以追问,