Kapil leaves his house 20 minutes before six in the morning.
Six in the morning is 6:00 AM.
20 minutes before 6:00 AM is 5:40 AM.
Kapil travels for 25 minutes to reach Kamal's house.
Time of departure: 5:40 AM
Travel time: 25 minutes
Time of arrival at Kamal's house:
5:40 AM+25 minutes
=6:05 AM
They finish their breakfast in 15 minutes.
Breakfast starts at: 6:05 AM
Breakfast duration: 15 minutes
Breakfast ends at:
6:05 AM+15 minutes
=6:20 AM
They leave for their institute immediately after finishing breakfast.
Therefore, they leave Kamal's house at 6:20 AM.
Answer: 6:20 AM (as per answer key)