Question

answer this question

Answer 1

Let the distance of a one side trip be d.

For one side of the trip, average speed is 20kmph.
So time for the journey = distance / speed
= d/20

For the other side of the trip, average speed is 30kmph.
So time for the journey = distance / speed
= d/30

net average speed = total​ distance/total time

= (d +d )/(d/20+d/30)
= 2d/(d/20+d/30)
= 2/(1/20+1/30)
= 2/ (5/60)
= 24 kmph

Hence, the net average speed of Abdul's journey is 24 kmph.

Hope you understand the concept.
All the best.