HW Q11I need help on my homework

The average number of vehicles waiting in a line to enter a parking ramp can be modeled by the function f( X ) = 2(1 - x) where x is a quantity between 0 and 1 known as the traffic intensity. Find the rate of change of the number of vehicles in line with respect to the traffic intensity for x = 0.6. The rate of change for x = 0.6 is (Simplify your answer. Type an integer or decimal rounded to four decimal places as needed.)