Question 3: If the distance from A to the top of the mountain is X, then the distance from B to the top of the mountain is 23.5-X. ..

Then X/3+(23.5-X)/5=6.5.

The solution is X= 13.5.

He went up the mountain from B's original road, crossed the top of the mountain and returned to A.

Time = (23.5-13.5)/3+13.5/5 =181/30 (hours)