How fast do the buses together travel? 74+76kph, or 150kph. They only need to travel 15k to meet. 15k/150kph= 1/10th of an hour. An hour is 60 minutes long, so 1/10 of that time would be 6 minutes to meet.
I'm sure your instructor wants the meet time. The PASS time would have to include the length of the buses and you'd add seconds ;-)