Intermediate Algebra for College Students (7th Edition)

$h=\dfrac{3V}{\pi{r^2}}$
Multiply 3 to both sides: $3\cdot V=3 \cdot \frac{1}{3}\pi{r^2}h \\3V=\pi{r^2}h$ Divide by $\pi{r^2}$ on both sides: $\dfrac{3V}{\pi{r^2}} = \dfrac{\pi{r^2}h}{\pi{r^2}} \\\dfrac{3V}{\pi{r^2}} = h \\h=\dfrac{3V}{\pi{r^2}}$