The distributive property tells us that
color(white)("XXXX")(color(red)(a)+color(blue)(b))(color(green)(p)-color(orange)(q)) = (color(red)(a)+color(blue)(b))color(green)(p) - (color(red)(a)+color(blue)(b))color(orange)(q)
and that
color(white)("XXXX")(color(red)(a)+color(blue)(b))color(green)(p) = color(red)(a)color(green)(p)+color(blue)(b)color(green)(p)
Therefore
color(white)("XXXX")(color(red)(2x^2)+color(blue)(y^2))(color(green)(x)-color(orange)(2y))
color(white)("XXXX")(color(red)(2x^2)+color(blue)(y^2))color(green)(x) - (color(red)(2x^2)+color(blue)(y^2))color(orange)(2y)
color(white)("XXXX")=(color(red)(2x^2))(color(green)(x)) +(color(blue)(y^2))(color(green)(x)) - (color(red)(2x^2))(color(orange)(2y)) - (color(blue)(y^2))(color(orange)(2y))
color(white)("XXXX")=2x^3+xy^2 -4x^2y-2y^3