Because:
(4) is the correct answer.
Because
15(xy - y2- x + y)
= 3(x-y)(y-1)
= 3(y-1)
10(x2 -
yx -x + y) 2(x-y)(x-1) 2(x-1)
Because
15(xy - y2- x + y)
= 3(x-y)(y-1)
= 3(y-1)
10(x2 -
yx -x + y) 2(x-y)(x-1) 2(x-1)