Explanation:
in its basic structure such a prism is like a cube (just rectangular and not squared) : 6 sides (rectangles).
2 rectangles top and bottom 6×8 = 48 m²
48 × 2 = 96 m²
2 rectangles front and back 6×4 = 24 m²
24 × 2 = 48 m²
2 rectangles left and right 8×4 = 32 m²
32 × 2 = 64 m²
the total surface area is
96 + 48 + 64 = 208 m²
it is hard to find other integer dimensions for the same surface area.
but as long as we are not restricted to integer numbers :
let's cut e.g. the height in half.
and we get
2 rectangles left and right 8×2 = 16 m²
16 × 2 = 32 m²
that "nails" already 2 dimensions (width and height).
we need to set now the third dimension (length) to create the same surface area :
length×8×2 + length×2×2 = 208 - 32 = 176
20×length = 176
length = 8.8 m
so, with
length = 8.8 m
width = 8 m
height = 2 m
we still get
2 rectangles top and bottom 8.8×8 = 70.4 m²
70.4 × 2 = 140.8 m²
2 rectangles front and back 8.8×2 = 17.6 m²
17.6 × 2 = 35.2 m²
2 rectangles left and right 8×2 = 16 m²
16 × 2 = 32 m²
as total surface area
140.8 + 35.2 + 32 = 208 m²