Simplify (y^2 + 10xy^2-9x + 11x^2) -(8x^2-55xy -4y2) + (-8y^2-11x^2-9xy)

=(y^2 + 10xy^2-9x + 11x^2) -(8x^2-55xy -4y2) + (-8y^2-11x^2-9xy)

=y^2 + 10xy^2-9x + 11x^2-8x^2+55xy +4y2-8y^2-11x^2-9xy

=y^2+4y2-8y^2 + 10xy^2 + 11x^2-8x^2-11x^2 -9x +55xy-9xy

=-3y^2 +10xy^2 -8x^2 -9x+46xy