4 hours
4
12pm to 7pm is a span of 7 hours.
3 hours between 12pm and 3pm
21
It is 24 hours.8am to 8pm = 12 hours.8pm to 8am = 12 hours.2 x 12 = 24.
12 hours
On the same morning there are 3 hours from 8am to 11am
6 hours.
20
2
-6
14 hours
Eight hours !