Having a bit of trouble with this one. Can anyone help?

Many thanks.The surface are, S, of a cylinder is given by S = 2 r

Q.^{2}+ 2 rh. Its volume, V, is given by V = r^{2}h. Express V in terms of S & r only.

Attempt:V = S => r^{2}h = 2 r^{2}+ 2 rh => r^{2}h = 2 (r^{2}+ rh) => V = ...

Ans.:V = (S - 2 r^{2})