Answer: 31.5 rolls
Explanation:
A room is to be wallpapered including the ceiling and floor and the room is 18 feet long by 10 feet wide by 7 feet high. The total area covered by the room will be: length × width × height
= 18 × 10 × 7
= 1260 feet
A roll of wallpaper covers 40 ft. The number of rolls to buy will be:
= 1260 ÷ 40
= 31.5 rolls