1. Right sides are identical ====> hence, left sides are equal: x^3 = y^3. 2. Since x and y are integer, the last equality implies x = y. 3. Then the either of the two given equations is equivalent to x^3 = 89x + 40x, or x^3 = 129x, x*(x^2-129) = 0. In integer numbers, the last equation has only one solution x= 0. Answer. The only solution to the original system in integer numbers is the pair (x,y) = (0,0).