A driver takes 0.2 sec to apply brake.if the speed was 54 km/sec and retardation 6m/sec find the distance moved by the car on comming to rest after application of brake?

I suspect both the speed and retardation are given with incorrect units. I assume the latter is 6 m/s^2.

Before application of brakes, the vehicle travels
  (54 km/s)(0.2 s) = 10.8 km

After application of brakes, the vehicle travels
  (54 km/s)^2/(2*6 m/s^2)
  = 54^2/.012 km
  = 243000 km

The vehicle takes a total of 243,010.8 km to stop.