To stop a car, first you require a certain reaction time to begin braking; then the car slows under the constant braking deceleration. Suppose that the total distance moved by your car during these two phases is 53.8 m when its initial speed is 77.9 km/h, and 23.1 m when its initial speed is 47.1 km/h. What are
(a) your reaction time and
(b) the magnitude of the deceleration?