To find out the time in between a different time you can add in segments, you can add 15min to 2:45, to make it 3:00, then add 60 more minutes to make it 4:00, so now we have 75 min, then add 20 minutes to get the time to 4:20 pm, you then add up all the segments, which equal 95 minutes. In hours it would be 1 hour, and 35 minutes. Hope you understand that, of not, tell me, and ill fix it and make it more understandable.