Answer:
If it opens at 5:30, then it closes at 10:00 AM
If it opens at 6, then it closes at 10:30 AM
If it opens at 6:30, then it closes at 11:00 AM
If it opens at 7, then it closes at 11:30 AM
If it opens at 7:30, then it closes at 12:00 PM
After 12:00 PM, no one is going to have breakfast. So these are the only possibilities of the timing it will open. Either at 5:30, 6, 6:30, 7, or 7:30.
