One can of paint of paint covers 250 ft^2. how many cans of paint do you need to paint one coat on the walls of a room that is 12.5 ft by 20 ft?
You can’t answer this without knowing the height of the walls.
If the height is 8 ft, then you have two walls that are 12.5 x 8, and two walls that are 20 x 8. So the total area of the walls is
212.58 + 2208 = 520 sq ft.
The area of the windows and door is
23.54 + 3*7 = 49 sq ft.
Subtract the two area to get the paintable area.
520 - 49 = 471 sq ft.
1 can only covers 250, but two cans covers 500, which is enough for 471.