You need to analyze the information given in the exercise.
You know that he wakes up at 6:45 a.m. So notice that you can divide this time in hours and minutes. This would be: 6 hours and 45 minutes.
Since he takes 15 minutes to get dressed, you need to add 15 minutes to the 45 minutes shown above:
You need to remember that 60 minutes is 1 hour. This means that 6 hours and 45 minutes plus 15 minutes is:
Now you have 7 hours and 0 minutes. So, if you add 30 minutes (the time he takes ti eat his breakfast):
The answer is: