Braking distance: Distance travelled after the brakes are applied.
Total stopping distance = Braking distance + Distance travelled in the reaction time

Case A:
Deceleration = 6.0 m/s²

For driver X:
Initial velocity, u = 54 km/h = 15 m/s
Final velocity, v = 0
Braking distance,

a=02-1522-6≈19m

Distance travelled in the reaction time = 15 × 0.20 = 3 m
Total stopping distance, b = 19 + 3 = 22 m

For driver Y:
Initial velocity, u = 72 km/h = 20 m/s
Final velocity, v = 0
Braking distance,

c=02-2022-6≈33m

Distance travelled in the reaction time = 20 × 0.30 = 6 m
Total stopping distance, d = 33 + 6 = 39 m

Case B:
Deceleration = 6.0 m/s²
Now, we have:
e = 15 m
f = 18 m
g = 27 m
h = 33 m