What should be added to `2x^(3)-y^(3)+3y-3` to get `x^(3)+y^(3)+2y+1?`

What should be added to x^3 + 3x^2y + 3xy^2 + y^3 " to get " x^3 + y^3 ?

What should be added to x y-3y z+4z x to get 4x y-3z x+4y z+7?

What should be added to x y-3y z+4z x to get 4x y-3z x+4y z+7?

x^(3)-y^(3)+3y^(2)-3y+1

What should be added to x y+y z+z x to get x y-y z-z x ? (a) -2x y-2y z-2z x (b) -3x y-y z-z x (c) -3x y-3y z-3z x (d) 2x y+2y z+2z x

What should be subtracted from x+2y-3z to get 3x-2y +z ?