Answer: Hence, there is 5 gallons of fuel Roselyn needed for her journey.
Explanation:
Since we have given that
Speed at which Roselyn wants to drive her car = 60 miles per hour
Time taken by her car = 1.5 hours
As we know the formula for "Distance-Speed " :

Her car has fuel efficiency = 15 miles per gallon
Number of gallons of fuel is given by

Hence, there is 5 gallons of fuel Roselyn needed for her journey.