We can add the minutes from 7:20 AM to the next hour (8:00 AM), that is 40 minutes.
Then, from 8:00 AM to 9:00 AM we have 60 more minutes.
Then, from 9:00 AM to 9:49 AM we have 49 additional minutes.
We add all three segments as:

As 60 minutes is 1 hour, 120 minutes is 2 hours. Then, 149 minutes are 2 hours and 29 minutes.
Answer: the time elapsed us 149 minutes (or 2 hours and 29 minutes)