$240
Since a square yard is 3ft x 3ft, a square yard is equal to 9 square feet. Dividing 180 square feet by 9 square feet, we find that the room is 20 square yards.
Since carpet is $12 per square yard, and we have 20 square yards to cover, by multiplying 20 by $12, we find that the room will cost $240 to cover.