First find the square feet of each room and then add those together:
12 feet x 12 feet = 144 square feet
10 feet x 14 feet = 140 square feet
21 feet x 20 feet = 420 square feet
144 + 140 + 420 = 704 square feet total.
1 square foot = 0.111 square yards.
Multiply total square feet by 0.1111 to find the square yards:
704 x 0.111 = 78.2 square yards. Round your answer as needed.