A train is moving parallel and adjacent to a highway with a constant speed of 30 m/s. A car is traveling in the same direction as the train at 57 m/s. The car's horn sounds at 570 Hz and the train's whistle sounds at 330 Hz. When the car is behind the train what frequency does an occupant of the car observe for the train whistle? The speed of sound is 343 m/s.