Jim and his family are touring Chicago. They want to visit the Willis Tower, hang out at Navy Pier,

Jim and his family are touring Chicago. They want to visit the Willis Tower, hang out at Navy Pier, and shop on Michigan Avenue before their dinner reservations at 4:15 P.M. They plan to spend 1 hour and 25 minutes at the Willis Tower, 1 hour and 40 minutes at Navy Pier, and 1 hour and 40 minutes shopping. What is the latest time Jim's family can start their tour of Chicago and still make it to dinner on time?

First thing we want is how much time is Jim's family spending on pre-dinner activities

1. 1 hour and 25 minutes at Willis Tower
2. 1 hour and 40 minutes at Navy Pier
3. 1 hour and 40 minutes shopping

Add these all up and we get:
3 hours and 105 minutes
105 minutes = 60 + 45
3 + 1 hours = 4 hours and 45 minutes

IF dinner reservations start at 4:15, the latest Jim's family can start their tour is:
4:15 pm and go back 4 hours and 45 minutes

We go back 5 hours and we get 11:15 am
and add 15 minutes to get 11:30 AM

4:15 pm and go back 4 hours to get 12:15 pm
Now go back another 45 minutes and we get 11:30 am