A car is traveling at a constant velocity. At t = 3 s, the position of the car is at x = +50 m, and at t = 7 s, the position of the car is at x = 40 m. What is the velocity of the car in m/s, km/h, and mph?

A car is accelerating at a constant rate. At t = 2 s, the velocity is v = 15 m/s, and at t = 5 s, the velocity is v = 21 m/s. What are the magnitude and the direction of the acceleration?