Question 794372
(-5xy^2 + 3xy - 9y^2) - (6xy^2 + 7xy - 8y^2)
group like terms:
(-5xy^2 - 6xy^2) + (3xy - 7xy) + (-9y^2 + 8y^2)
-11xy^2 - 4xy -y^2
y(-11xy - 4x - y)