I'm kind of confused on this one.. please tell me how you got the answer as well.
These are alwas a little difficult
-4y^2 + 3xy - 12y + 9x factor by grouping
y ( -4y + 3x) + 3 (-4x + 3x)
Take out the commmon factor and then write the rest in parentheses
(-4y + 3x) ( y + 3) =
(3x - 4y) ( y + 3)