We were told that the car travels 360 miles in 8 hours.
Recall that
Speed = distance/time
Speed of the car = 360/8 = 45 miles per hour
Since the speed is constant, it means that the constant speed of the car is 45 miles per hour.
Also,
Time = distance/speed
For the car to travel 168 miles,
Time = 168/45
= 3.73 hours