Answer: 400
Step-by-step explanation:
Perimeter of the base = 8+10+15+7+23+17 = 80 meters
The 23 is from 8+15 = 23 and it is the length along the back wall, while the 10+7 = 17 is the length along the left side wall. Both the sides of 23 and 17 are hidden from view. The height of 5 meters is not part of the perimeter of the base.
Multiply the perimeter of the base by the height of the building to find the lateral area, aka wall area.
80*5 = 400 square meters