Since the acceleration of car is uniform so the distance traveled by car while brakes are applied is given by
[tex] d = \frac{v_f + v_i}{2}*t[/tex]
given that
[tex]v_f = 9 m/s[/tex]
[tex]v_i = 15 m/s[/tex]
[tex]t = 1.20 s[/tex]
now plug in all data in above formula
[tex]d = \frac{15 + 9}{2} * 1.2 [/tex]
[tex] d = 14.4 m[/tex]
so car will cover 14.4 m distance while it apply brakes