The volume at a section of a 2-lane highway is 1800 vph in each direction and the density is approximately 30 bpm. A slow moving truck joins the traffic streams and travelers for a length of 3 miles at 25 mph. There is no option for following vehicles to pass the truck due to large opposing traffic volume. The platoon forming behind the truck has a density of 100 bpm and a flow rate of 1100 vph. How many vehicles are in the platoon before the truck leaves the highway