Agraphing calculator is recommended a highway engineer wants to estimate the maximum number of cars that can safely travel a particular highway at a given speed. she assumes that each car is 15 ft long, travels at a speed s, and follows the car in front of it at the "safe following distance" for that speed. she finds that the number n of cars that can pass a given point per minute is modeled by the following function. 88s n(s) = 15 + 15 17 at what speed can the greatest number of cars travel the highway safely?