We know the movie started at 2:35
The movie lasted 1 hour and 45 minutes, so simply 1:45 (hours:minutes)
Add 2:35 with 1:45 so,
2:35 + 1:45 = 3:80
There can only be 60 minutes maximum, and 60 minutes = 1 hour, so convert the excess amount of 80 minutes to hours (which equals 1 hour and 20 minutes)
Simply add 1 to the hours and the minutes go back to 20 (since we've subtracted 60 from 80)
The movie ended 4:20