D.24 Got over a pass

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.












Answer
48 km