[tex] \bf \textit{surface area of a cylinder}\\\\
SA=2\pi r(h+r)~~
\begin{cases}
\textit{units all tripled}\\
h=3h\\
r=3r
\end{cases}\implies SA=2\pi (3r)(3h+3r)
\\\\\\
\begin{cases}
r=\stackrel{mm}{4}\\
h=\stackrel{cm}{1.5}\\
~~~~\stackrel{mm}{15}
\end{cases}\implies SA=2\pi (12)(45+12)\implies SA=24\pi (57)
\\\\\\
SA=1368\pi [/tex]
now, recall, the exercise is assuming you're using π = 3.14.
