Answer:
There lesson last for 2 hours and 25 minutes.
Step-by-step explanation:
Minus 840 (8:40) and 615 (6:15) and you get 225 (2:25)
2 hours 25 minutes
Add minutes step by step.
6:15 --> 7:00
= 45 minutes
7:00 --> 8:00
= 1 hour
8:00 --> 8:40
= 40 minutes
40 min. + 45 min. + 1 hour = 2 hours 25 minutes
