The answer to this question would be: 5 second
In this question, you are given the initial distance (300ft), car velocity(48ft/s) and the final distance(60ft). You are also given the equation to calculating the distance, so this question should be easier. The question is when the time where the distance is 60 ft. So the answer would be:
distance= 300-48t
60 = 300ft- 48t
48t= 300- 60=240
t= 5