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?

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.)

In this problem it decreased 20%