General: Traffic Safety Traffic fatalities have decreased over recent decades, with the...

General: Traffic Safety Traffic fatalities have decreased over recent decades, with the number of fatalities per hundred million vehicle miles traveled given approximately by , where x stands for the number of five-year intervals since 1985 (so, for example, x = 2 would mean 1995). Find the rate of change of this function at:

a. x = 4 and interpret your answer.

b. x = 9 and interpret your answer.