Alexis needs to paint the four exterior walls of a large rectangular barn. The length of the barn is 80 feet, the width is 50 feet, and the height is 30 feet. The paint costs $28 per gallon, and each gallon covers 420 square feet. How much will it cost Alexis to paint the barn? Net of the barn

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Length: 80 ft

Width: 50 ft

Height: 30 ft

I need help on the highlighted section, please help and explain (so I can understand).

Step 1: Find the area of the 4 walls

Find the area of the front and back walls

Find the area of the left and right walls

Add them together

Area= 7,800ft^2

Step 2: Find how many gallons of paint you need using your answer from step 1 if ONE gallon covers 420 square feet.

Gallons

Area Covered

1

6

12

18

19

20

Step 3: Find how much money it will cost to purchase the number of gallons above if 1 gallon costs $28