When you sneeze, the air in your lungs accelerates from rest to approximately 160 km/hr in about 0.55 seconds . what is the acceleration of the air in m/s2?

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

80.8 m/s² (nearest tenth)