Debra's room is 4m long, 3.5 wide and 2m high. She wallpapers all 4 walls excluding a door which is 2m by 1m and a window which is 1m by 1m. If the wallpaper costs $3 per m square, how much cost of wallpapers?
perimeter = 2*4 + 2*3.5
= 8 + 7
= 15 meters
total area = 15 * 2 = 30 m^2
now subtract 2 and 1 = 3
so
27 m^2
27*3 = 81 dollars
But not really if you ever did wall paper :) It never comes out like that perfectly, has to be lined up and edged perfectly so needs extra.