Answer:
There are 5 surfaces for which you will have to calculate area.
the back is 4 by 8 = 32 mi^2
The bottom is 4 by 6 = 24 mi^2
the tilted ramp 4 by 10 = 40 mi^2
There are 2 side triangles 8 by 6 area of 1 triangle = 8*6/2 = 24 mi^2
area of BOTH triangles = 2 * 24 = 48 mi^2
Total area = 32 + 24 + 40 + 48 = 144 mi^2
Explanation: