8 hours.
8 Hours 30 Mins
Nine and a half hours.
840
Nine hours.
4.5 hours
ten and a half
8:30am to noon is 3.5 hours.
It is (8.5 + 24k) hours where k is an integer.
Assuming you mean on the same day... 5 hours 30 minutes.
8 hours and 30 minutes.
1960