When 4x-x^2-4y+xy is factored completely, one of the factors is?

The y terms are xy - 4y = y * (x - 4) where * is the multiplication symbol.

The other two terms are 4x - x^2 = x * (4 - x) = (-x) * (x -4) (negated for a match to the y terms)

so when factored we get (x - 4) * (y - x) = (4 - x) * (x - y) (negated to get one of the four answers.)

The answer is (c) (4 - x)

4x - x^2 - 4y + xy
= -x^2 + 4x + xy - 4y
= (-x^2 + 4x) + (xy - 4y)
= -x(x - 4) + y(x - 4)
= (x - 4)(-x + y) or (4 - x)(x - y)
(answer c)

First -x(x-4) + y(x-4) then (x-4)(y-x) so (x-y)(4-x) the proof that
c. is the answer.

4x-x^2-4y+xy
Factor by grouping:
x (4-x) -y(4-x)
(4-x) (x-y)

The answer is c