so hmm notice the picture below
so V = l*w*h
thus [tex]\bf V=lwh\qquad
\begin{cases}
l=2\\
w=5\\
\end{cases}\implies V=2\cdot 5\cdot h\implies \boxed{V}=10h
\\\\\\
V=\cfrac{m}{d}\qquad
\begin{cases}
m=mass\\
d=density\\
----------\\
m=10\\
d=0.5
\end{cases}\implies V=\cfrac{10}{0.5}
\\\\\\
\boxed{10h}=\cfrac{10}{0.5}[/tex]
solve for "h"