Distance traveled is measured in kilometres. The time it take to travel the distance is given in hours. So, we express the average speed in kilometres per hour (km/h). If the distance is given in metres, the average speed will be in metres per hour (m/h). If the time is given in seconds, the average speed will then be in metres per second (m/s).

#### Example:

A car travels a distance of 150 km in 3 hours. Calculate its average speed.

Average speed = distance ÷ time = 150 ÷ 3 = 50 km/h