You will need to use this formula:
V = Vo + a x t
V - Final velocity // If it comes to a complete stop,it will be 0 m/s.
Vo - Initial velocity = 27 m/s
a - Acceleration = ? m/s^2 // All units are in S.I
t - Time = 14 secs
So:
-> 0 = 27 + a x 14
-> 14a + 27 = 0
-> 14a = -27
-> a = -27/14
-> a = -1.928... m/s^2
Rounding to the nearest hundredth: -1.93 m/s^2.
Answer: The acceleration of the car is -1.93 m/s^2.