3х+ху^2-х^2у-3у

To simplify the expression 3x + xy^2 - x^2y - 3y, we can factor out common terms:

3x + xy^2 - x^2y - 3y = 3x - 3y + xy^2 - x^2y = 3(x - y) + y(x - x^2) = 3(x - y) + y(x(1 - x)) = 3(x - y) + yx(1 - x) = 3(x - y) + yx(1 - x)

Therefore, the simplified expression is 3(x - y) + yx(1 - x).