Change in velocity, Δv = 160 km/hr
Change in time, Δt = 0.55 s
Note that
1 km = 1000 m
1 h = 3600 s
Therefore
Δv = (160,000 m/h)*(1/3600 h/s) = 44.4444 m/s
By definition, the acceleration is
a = Δv/Δt = (44.4444 m/s)/(0.55 s) = 80.808 m/s²
Answer: 80.8 m/s² (nearest tenth)