An AGV train delivers empty pallets from the end of a production line back to the beginning so they can be used again. The line is feet long. Each trailer on the train holds four pallets, and each pallet takes seconds to load onto a trailer. Releasing a train takes an additional seconds after it is loaded. Another seconds per pallet and seconds per train are required at the other end of the trip to unload. The train travels at feet per minute. Production rate on the line is parts per hour, requiring pallets per hour.

How many trailers will be needed on a single train to keep up with the flow of pallets?