Answer: 4.8 hours.
Explanation:
To find how long it would take to travel the same distance at a slower speed, find the speed the car is currently driving at.
Speed is distance over time, or in this case, miles per hour.
360 / 4 = 90 miles per hour.
The car is travelling 15 miles per hour slower, so the new speed is 90 - 15, or 75 miles per hour.
You can now use the same equation to find the time travelled:
360 / x = 75
360 = 75x
Divide both sides by 75 to get your answer:
4.8 = x
It would take the car 4.8 hours to travel the same distance.