Acar drives to the east in a time of 6 hours. then, immediately (not realistic, but just assume this is the case for this problem), travels 12 km to the west in 3 hours. the average speed for the entire trip is 8 km/hr. what is the average speed of the car for the first part of the trip, in km/hr, while the car was traveling east?

Average speed of car in the first trip is 10 km/hr    

Explanation:

It is given that first the car drives 6 hours to the east

Then travels 12 km to west in 3 hours

Average speed for the entire trip = 8 km/hr

Total time = 3+6 = 9 hour

So distance traveled in 9 hour = 9×8 = 72 km

As the car travel 12 km in west so distance traveled in east = 72-12 = 60 km

Time by which car traveled in east = 6 hour

So speed

So average speed of car in the first trip is 10 km/hr