What is the time of 2 hours and 45 minutes elapsed in the end time is 7: 31 p. m.

The question is asking that we find the start time. It took 2 hours and 45 minutes to get to the time 7:31 p.m. We know that not that much time went by so the start time would still be p.m. To make it an even number we can take 1 minute away from the time to make it 7:30 and 2 hours and 44 minutes left to go backwards. An hour before 7:30 is 6:30. That is a whole 60 minutes. Another hour is 5:30. Now we need to subtract 44 minutes from that still. We can start by taking 30 minutes away from the 44 minutes remaining to make the time 5:00 and the remaining amount: 14 minutes. To find the final start time we know that it is going to be during the 4:00 hour. So we are going to take the amount of minutes inside one hour and subtract the 14 minutes remaining to get the minutes section of the time. 60-14=46. So the time is 4:46 p.m. 

The answer would be 4:46 because 2 hours and 45 minutes befor 7:31 would be 4:46