There are 24 hours in a day. The first 12 of them are called "am" (from the Latin ante meridiem, meaning "before midday"), the last 12 are called "pm" (from the Latin post meridiem, "after midday").
Of cause if you use a 24 hour clock the terms "am" and "pm" are not needed.
5 hours and 15 minutes.
6 hours and 30 minutes.
Two hours elapsed time.
It is 13 + 24 k hours (where k is any integer) and 30 minutes.
12:45 pm
12 hours
12 hours
12 Hours ! There are 12 hours in the AM and 12 hours in the PM !
From midnight (am) to Noon (pm) is 12 hours.
At 1mph it will take you 1115 hours. Have fun!
2.5 hours
21 hours