Question

Christopher is going to install wallpaper on the four walls of his room. Two of the walls are 14 feet long by 9 feet high. The other two walls are 20 feet long by 9 feet high. His options at the wallpaper store are below.
One single roll of wallpaper costs $20 and covers 18 square feet of area.

One double roll of wallpaper costs $40 and covers 54 square feet of area.

What is the minimum cost of installing the wallpaper on the four walls of Christopher's room?

Answer 1

Dear Oliwia123grych, let's go step by step. The walls are 14 ft x 9 ft, so if  we multiplied 14 by 9, we get the area 126 ft². The other walls are 20 x 9 ft, so if we multiplied 20 by 9, we get the area 180 ft². Add the area together to get 306 ft² total. To make the process simpler, let's find the unit rate for each square feet of area for each type of wallpaper. The first one is $1.11. The other one is $0.70. Since the second unit rate is smaller. Let's divide first, then multiply. 180/54 gets us 3.33 double rolls of wall paper. Then we do 3.33 times 40 to get $133.20 minimum. (Please rate this brainiest. I worked really hard on this problem.)