Well, we have the equation S=2 * pi * r * h.
We're solving for h. So that means we have to isolate h.
First, we divide both sides by 2 to get S/2 = pi * r * h
Then we divide both sides by pi to get S/(2pi) = r * h.
Finally, we divide both sides by r to get S/(2*pi*r) = h
So h = S/(2*pi*r)
And that's our answer