-- The left side wall and the right side wall are each (15 x 9) = 135 square ft.
-- The front wall and the back wall are each (12 x 9) = 108 square ft.
-- The total area of all 4 walls is (135 + 108 + 135 + 108) = 486 square ft.
-- You need 1 gallon of paint for every 425 square ft.
How many times will you need to cover 425 square ft ?
486 / 425 = 1.144 times
-- So you need 1.144 gallons in order to paint all 4 walls.
When rounded to the nearest 1/10th gallon, the number is 1.1 gallons.
That choice is not found on the list of choices given with the question.
-- Even so, that figure of "1.1 gallons" is probably a little more than you
actually need in order to paint the 4 walls . . . That quantity of paint includes
enough to paint over the door, the windows, and all of the electrical outlets !
