Each wall measures 12 ft * 14 ft.
Area of one wall = LW = 12 ft * 14 ft = 168 ft^2
Area of 3 walls = 3 * area of 1 wall = 3 * 168 ft^2 = 504 ft^2
One roll of wall paper covers 42 ft^2.
To find out how many rolls are needed,
divide the total area by the area of one roll.
(504 ft^2)/(42 ft^2) = 12
Answer: Shae should purchase 12 rolls.
