What it is asking you to do is solve for h rather than V. You want h all by itself on one side of the equation.
Step One
Multiply both sides by 3
3*V = 3*(1/3 [tex] \pi [/tex]r²h
3V = [tex]\pi[/tex]r²* h Divide both sides by r²
[tex] \dfrac{3*V}{r^{2}} = \pi * h [/tex] . . . . . . Divide by pi
[tex] \dfrac{3*V}{ \pi * r^{2}} = \dfrac{\pi * h}{\pi} [/tex]
[tex]\text{h =} \dfrac{3*V}{ \pi * r^{2}}[/tex] <<<<<< Answer