Answer:
45 minutes.
Explanation:
You can ignore the 1:15 pm, as it's not relevant to the question of how much time you have spent in class.
11:45am to 12:30pm
Adding 15 minutes turns 11:45 am to 12:00 pm
Add another 30 minutes, it becomes 12:30 pm.
Calculate the sum of the minutes:
15+30 = 45 minutes.