James Bond is riding a bike at 15 m/s, chasing Car #1 moving in the same direction at 35 m/s. Behind James is another car, Car 2, chasing him at 20 m/s. Both cars have horns blaring at a frequency of 390 Hz. Assume a sound speed of 340 m/s.
a. What frequency does James hear from Car 1?
b. From Car 2?
c. What is the beat frequency he hears?