This question is about elapsed time.
Let's solve this step-by-step.
1.) 1:35 PM is a tricky time to deal with. Let's change it to 2:00 PM by adding 25 minutes. There are 60 minutes in an hour. Therefore, 35 minutes + 25 minutes, or 60 minutes, makes it 2:00 PM.
1:35 PM => 2:00 PM (+25 min)
2.) Now, let's add one more hour to make it 3:00 PM.
2:00 PM => 3:00 PM (+60 min)
3.) Now, simply add 30 minutes to make it 3:30 PM.
3:00 PM => 3:30 PM (+30 min)
4.) Now, add the time up together.
25 + 60 + 30.
=> 85 + 30
=> 115 minutes
5.) Joy was on the train for 115 minutes. (It asked for minutes.)