It depends on the width of the carpet.
The room is 144 square feet.
144 sq. feet
144 square feet. (12 x 12 = 144) or 16 square yards.
108 square feet
11x14=154 square feet If you are ordering carpet, it comes in 12 widths. 14 linear feet would be needed. Buy 168 square feet.
You need a price for the carpet, per square foot, to find the answer.
The 12 x 20 foot room has an area of 240 square feet, and the 15 x 15 foot room has an area of 225 square feet. That's 465 square feet of carpet. But hold the phone. Carpet is generally sold by the square yard, and a square yard is 9 square feet (as 3 feet x 3 feet is 9 square feet). The 465 square feet of floor is 51.666... or 52 square yards of carpet. It might be necessary to buy some "extra" area depending on the width of the "stock" roll of carpet from which the desired pattern/color of carpet is going to be cut.