A)
A man covers a distance of 15 km in 3 hour
Speed = total distance travelled/total time taken
Total distance travelled = 15 km
Total time taken = 3 hour
So, speed = 15/3 = 5km/h
Distance covered = speed x time
Distance covered by him in 5 hours = 5x5 = 25km
B)
Time taken = Distance travelled/speed
Time taken to cover 10 km = 10/5 = 2 hours