You can
put this solution on YOUR website!X=number of car passing in an interval of time
X~Poisson (mean=80/hour) or Poisson (mean 80/60min=4/3min)

where x>=0)
P(at least one car)= 1- P(no cars passing in the interval of interest)
P(X>=1)= 1-P(X=0) =

= 1-0.264=0.736