Answer: 5 meters
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Step-by-step explanation:
The floor is a 7 meter by 5 meter rectangle. The perimeter is
P = 2(L+W)
P = 2(7+5)
P = 2(12)
P = 24
The perimeter of the floor is 24 meters.
Multiply this perimeter by the unknown height h to get 24h
This expression represents the lateral surface area. This is the combined wall area. Set this equal to 120 and solve for h.
24h = 120
h = 120/24
h = 5
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Check:
One pair of walls is 7 meters by 5 meters, giving an area of 7*5 = 35 square meters each. So far that's 2*35 = 70 square meters for these two walls combined.
The other pair of walls is 5 by 5. Each has an area of 5*5 = 25 which doubles to 2*25 = 50
The total wall area is 70+50 = 120 to confirm the answer.