I need help please

Question

A living room is 18 feet long and 10 feet wide. If the ceiling is 10 feet high, what is the total surface area of the four walls?

Answer 1

For this, you would just add up the area of each of the 4 walls (note, we are not removing any doorway or windows in this problem, as they did not include that information).

1. For this, your rectangle (open box) is 18x10x10
2. (2) walls are 18x10 = (2) 180 = 360
3. (2) walls are 10x10 = (2) 100 = 200
4. Add and you get the surface are (not including the ceiling) of all 4 walls = 560 ft²

Answer 2

2*18*10 + 2*10*10 = 360 + 200 = 560