21
There are zero hours between 9 am and 9 am.
6, 7, 8, 9 Therefore, there are 3 hours between 6am and 9am.
4 hours. 9am until noon is 3 hours and 1 more makes 4.
109 hours
4
9 + 24k hours where k is an integer.
Depends on which days 9am is on and what day 10 am is on.If these times are within the same day, it is 13 hours.
12 hours.
From 9am to 6:30pm is 9 hours and 30 minutes.
5 Hours
6 hours