Carlota needs to practice the pianofor 1 2/3 hours. She has been practicing for 3/4 of an hour. how much longer must she practice

11/12 of an hour = 55 min

11/12 hours left. 1 2/3 - 3/4 = 11/12. First, find the common denominator (12). The problem is now 1 8/12 - 9/12. Use the 1 in (1 8/12) to borrow. Multiply the denominator by 1 (12) and add that to the numerator. The question is now 20/12 - 9/12. I assume that you can finish it off from there.