Answer:
17.5m
Explanation:
You gotta do this:
0.81 x 1 = Top area
((0.8 x 0.1) ÷ 2) x 2 = left side and right side area
1 x 0.1 + Back Area
0.8 x 1 = Bottom
Add them all together and remember that the final answer has to be in metres, you get - 17.5m