若1/X - 1/Y＝3 求〔5X+2XY+5Y〕/〔X+4XY-Y〕的值

1/x-1/y=3
(y-x)/(xy)=3
y-x=3xy
x-y=-3xy
〔5X+2XY+5Y〕/〔X+4XY-Y〕
写错了吧
应该是〔5X+2XY-5Y〕/〔X+4XY-Y〕
=[5(x-y)+2xy][(x-y)+4xy]
=(-15xy+2xy)/(-3xy+4xy)
=(-13xy)/(xy)
=-13