Civil engineer wants to estimate the maximum number of cars that can safely travel on a particular road at a given speed. he assumes that each car is 14 feet long, travels at speed s, and follows the car in front of it at a safe distance for that speed. he finds that the number n of cars that can pass a given spot per minute is modeled by the function
n=(89s)/(14+14(s/17)^2))

at what speed can the greatest number of cars travel safely on that road? assume that the maximum possible speed of a car is less than 300.