(-5xy)^2(-xy)^3+(4x^2y-3x)(-x^3y^4)+x^5y^5
=25x^2y^2(-x^3y^3)+4x^2y*(-x^3y^4)-3x(-x^3y^4)+x^5y^5
=-25x^5y^5-4x^5y^5+3x^4y^4+x^5y^5
=-28x^5y^5+3x^4y^4