Answer: 13 1/8
Explanation: since he cut two pieces and each piece is 4 1/4 you’re going to add 4 1/4 to 4 1/2 which makes it two pieces and the sum would be 8 1/2 then you’re going to 8 1/2 from the original length, 21 5/8 which is going to leave you with the remaining length being 13 1/8.
Hope it helps:)