Velocity = distance / time
So: The time in which the wave propagates through air which is its medium along with the distance the wave travels so a point are needed to give us our velocity.
In this case we only have velocity and time
So lets rearrange our equation to fit what we are solving for: distance
Vt = d
Now plug in our values:
(330)(0.40) = d
d = 132 m
So the distance between you and your neighbor is 132 m as they perceive the sound at time t= 0.4 and a speed of sound of 330 m/s.