You are driving east at 25.0 m/s as you notice an ambulance traveling west toward you at

Question:

You are driving east at 25.0 m/s as you notice an ambulance traveling west toward you at 35.0 m/s. The sound you detect from the sirens has a frequency of 300 Hz.
(a) Is the true frequency of the sirens (1) greater than 300 Hz, (2) less than 300 Hz, or (3) exactly 300 Hz?
(b) Determine the true frequency of the sirens. Assume normal room temperature.