Correct option is A
Time taken while going = Distance / Speed = 10 Km/12Km/h = 5/6 hours
Time taken while returning = Distance / Speed = 10 Km/18 Km/h = 5/9 hours
The total time for the trip is the sum of the time taken while going and returning:
Total Time = (5/6) hours + (5/9) hours = 25/18 hours
The average speed:
Average Speed = Total Distance / Total Time
= 20 Km/(25/18) hours
= 20 km ×(18/25) hours = 14.4 Km/h
