Subtract 2 pi*r^2 from either side of the equation giving you
S - 2 * pi *r^2 = 2 * pi * r * h
Divide by 2 pi * r on either side of the equation which would give us
h = ( S - 2 pi r^2) / 2 pi r
We have made h the height of the surface cylinder when the formula of the surface area of a cylinder was presented to us.