If 1 / x minus 1 / y = 3, find (5x + 2xy-5y) / (x-4xy-y)

1/x-1/y=3
(y-x)/xy=3
y-x=3xy
So X-Y = - 3xy
The original formula = [5 (X-Y) + 2XY] / [(X-Y) - 4xy]
=[5(-3xy)+2xy]/[(-3xy)-4xy]
=-13xy/(-7xy)
=13/7

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