Check the picture below.
so let's get all the area of its rectangles and sum them up.
[tex]\stackrel{\textit{\large rectangles' area}}{\stackrel{\textit{left and right}}{2(4\cdot 4)}+\stackrel{\textit{front and back}}{2(5\cdot 4)}+\stackrel{\textit{top and bottom}}{2(5\cdot 4)}}\implies 16+40+40\implies \stackrel{total}{96}[/tex]
