A bus and a truck start from locations A and B, respectively, at the same time, heading towards each other. The two vehicles meet after 6 hours, and at the meeting point, the bus is $240 \mathrm{~km}$ away from location B. The bus arrives at location B, rests for one hour, and then returns to location A. It is known that the truck takes 15 hours to travel from location B to location A, and after arriving at location A, it also rests for one hour before returning to location B. How many hours have passed from the first meeting to the second meeting?
Journey problem.
From departure to the first meeting, it took 1 full journey;
From departure to the second meeting, it took 3 full journeys;
Since the speeds of the two vehicles remain constant;
Therefore, the two vehicles took $6 \times 3-6+1=13$ hours from the first meeting to the second meeting.