let me lie down this prism.
Check the picture below.
so the prism is really 6 rectangles stacked up to each other at the edges, so we can simply get the area of each rectangle and sum them up.
[tex]\bf \stackrel{rectangles}{\stackrel{\textit{top and bottom}}{2(3.5\cdot 9)}~~~~+~~~~\stackrel{\textit{left and right}}{2(9\cdot 5)}~~~~+~~~~\stackrel{\textit{front and back}}{2(3.5\cdot 5)}} \\\\\\ 63+90+35\implies 188[/tex]
