[tex]\bf \textit{lateral area of a cylinder}\\\\
LA=2\pi rh\qquad
\begin{cases}
r=radius\\
h=height\\ -----\\
LA=20\pi \\
r=2.5
\end{cases}\implies 20\pi =2\pi \cdot 2.5h
\\\\\\
\cfrac{20\pi }{2\cdot 2.5\pi }=h\implies \boxed{4=h}\\\\
-------------------------------\\\\
\textit{total surface area of a cylinder}\\\\
SA=2\pi r(h+r)\implies SA=2\pi \cdot 2.5(4+2.5)[/tex]
