Car B is traveling a distance d ahead of car A. Both cars are traveling at 60 ft/s when the driver of B suddenly applies the brakes, causing his car to decelerate at 12ft / (s ^ 2) It takes the driver of car A 0.75 s to react (this is the normal reaction time for drivers). When he applies his brakes, he decelerates at 15ft / (s ^ 2) . Determine the minimum distance d between the cars so as to avoid a collision.