Explanation:
It is given that,
Avril cycles 10 km at x km/h and then 14 km at y km/h.
We need to express the time for the journey as a single fraction.
We know that,
Speed = distance/time
or
time = distance/speed
Here, total distance = 10 +14 = 24 km/h
Total speed = x+y
So,

Hence, this is the required solution.