Answer
(a.) $h=\frac{3V}{B}$
(b.) $h=18\;cm$
Work Step by Step
(a.)
The given formula is
$\Rightarrow V=\frac{1}{3}Bh$
Multiply each side by $3$.
$\Rightarrow 3\cdot V=3\cdot \frac{1}{3}Bh$
Simplify.
$\Rightarrow 3 V=Bh$
Divide each side by $B$.
$\Rightarrow \frac{3V}{B}=\frac{Bh}{B}$
Simplify.
$\Rightarrow \frac{3V}{B}=h$
(b.)
The given values are $V=216\;cm^3$ and $B=36cm^2$.
Substitute both values into the result from part (a.)
$\Rightarrow \frac{3(216\;cm^3)}{36cm^2}=h$
Simplify.
$\Rightarrow \frac{648\;cm^3}{36cm^2}=h$
$\Rightarrow 18\;cm=h$
