B. The total area painted is 864; they must buy two cans of paint.
Explanation:
Step 1:
A rectangle's area can be calculated by multiplying its length and its width. The wall is made up of 5 different types of rectangular walls. All walls are 8 feet tall but the length varies.
Step 2:
The area of the 20 feet long wall =
![(length)(width)= (20)(8) =160,](https://img.qammunity.org/2021/formulas/mathematics/middle-school/esuj85vyvr9wnn6wqincnldvo3rsmapefk.png)
The area of the 10 feet long wall =
![(length)(width)= (10)(8) =80,](https://img.qammunity.org/2021/formulas/mathematics/middle-school/jd24uvpljvukwxo5thqyg9itu0bp8znc44.png)
The area of the 5 feet long wall =
![(length)(width)= (5)(8) =40,](https://img.qammunity.org/2021/formulas/mathematics/middle-school/y3nyrpkbmla3qjyo81zecpx74qp5qsq66v.png)
The area of the 4 feet long wall =
![(length)(width)= (4)(8) =32,](https://img.qammunity.org/2021/formulas/mathematics/middle-school/okpo97u2m5y84byaglwug881e9jlrdk957.png)
The area of the 15 feet long wall =
![(length)(width)= (15)(8) =120.](https://img.qammunity.org/2021/formulas/mathematics/middle-school/vo1bpghkik08q4b4mvfydjtc5fizaj3gcb.png)
The area of all the walls = 432 square feet.
Since there are two sides for every wall, total area =
square feet.
Step 3:
If one paint can covers 500 square feet,
the number of cans required to paint 864 square feet =
cans.
so 2 paint cans are needed to paint 864 square feet which is option B.