A lesson which takes 1hr 45 minutes starts at 10.35a.m. what time does the lesson end?

To find out what time the lesson ends, we need to add 1 hour and 45 minutes to the start time of 10.35am.

Adding 1 hour to 10.35am gives us 11.35am.
Adding 45 minutes to 11.35am gives us 12.20pm.
Therefore, the lesson ends at 12.20pm.