The average speed of the family : 70 km/h
Further explanation
Given
time = 2 hour
distance = 140 km
Required
The average speed
Solution
Distance is the length traveled by an object within a certain time
Average speed = total distance/total amount of time
Can be formulated :
Avg speed = d : t
Total distance traveled : 140 km
Total time : 2 hr
Avg speed = 140 : 2 = 70 km/h