ANSWER
4 1/5 ft^2 (or 21/5 ft^2)
Step-by-step explanation
Step 1: 12 ft of fabric that was 2 1/3 wide =
Step 2: He used 1/4 of the fabric to make a long set of curtains
Step 3: The rest of the fabric
Step 4: The rest to make 5 short sets
Hence, the area of the fabric used for each of the short sets is 4 1/5 ft^2.