Explanation:
normally there are 6 surface areas on a prism (or simply "box").
for the lateral surface area we ignore the indicated (shaded) areas as to and bottom. that leaves us with the 4 white ones.
so, we have 2 rectangles of 4×3 and 2 rectangles (the missing side lengths must be identical to the other specified lengths given the graphic, otherwise the sides would not fit together to build the prism) of 1.5×4.
the total lateral surface area is therefore
2×3×4 + 2×1.5×4 = 24 + 12 = 36 ft²