Answer :
13 feet wide x 8 feet tall = 104 square feet of wall
6 feet wide x 3 feet tall = 24 square feet of window
104 - 24 = 80 square feet of wall paper
13 feet wide x 8 feet tall = 104 square feet of wall
6 feet wide x 3 feet tall = 24 square feet of window
104 - 24 = 80 square feet of wall paper