I got over a pass after leaving the departure point and went to a certain destination and returned to the departure point through the way to which I came.
At this time it took 6 hours and a half of going and 7 hours and a half of returning.
Find the distance from a departure point to the destination.
The speed of going up the pass is 6 km/h and that of going down is 8 km/h.
There is no flat way on the way.