Assuming you mean on the same day... 5 hours 30 minutes.
8 Hours 30 Mins
3pm to 10pm is 7 hours.
14 + 24k where k is any integer.
13
3 hours between 12pm and 3pm
24 of course !
16.5 + 24*k hours where k is any integer.
5 hours
6 hours
2 hours
9 hours
13