Explanation:
I understand and assume that the front and back areas are straight up (and not inclined inwards).
only the left and the right sides are inclined inwards.
so, the surface area of the whole block consists of
4 rectangles (1 top, 1 bottom, 2 equal sides left and right).
2 equal isoceles trapezoids (front and back).
at the end we only need to add all 6 areas together to get the total surface area.
so, let's go through all 6 areas.
top = 8×12 = 96 cm²
bottom = 14×12 = 168 cm²
left side = right side = 5×12 = 60 cm².
both sides together : 120 cm²
front = back = (bottom line + top line) × h / 2 =
= (14 + 8) × 4 / 2 = 22 × 2 = 44 cm²
front + back = 88 cm²
the total surface area is
96 + 168 + 120 + 88 = 472 cm²