Average speed is the total distance traveled divided by the total time taken. Speed  = distance/time or time = distance /speed.

The distance from A to B is 900 km.

If a person walks from A to B at 5 km/h without stopping, the time taken to cover the distance is 900/5 = 180 hours.

If a person walks at 5 km/h for 10 h each day, the number of days required to cover the distance is 900/50 = 18 days.

If a person walks at 1.5 m/s without stopping the time taken to cover the distance is 900*1000/1.5 = 600000 seconds.