Atrip takes 7 3/4 hours and 2/3 of the trip is done how much longer to the end of the trip

Total trip time: 7 3/4
time spent: 2/3
time left: total time - time spent
= 7 3/4 - 2/3
=31/4 - 2/3
by taking lcm:
= (63-8)/12
=  55/12
= if in decimals: 4.583
= if in mixed numbers: 4  7/12
so the time left is 4 7/12 hours