1. The problem statement, all variables and given/known data A car moving at 35 m/s approaches a stationary whistle that emits a 220 Hz sound. The speed of sound is 343 m/s. What is the speed of sound relative to the driver of the car? 2. Relevant equations fo = fs [1 +/- vo/v] / [1 +/- vs/v] 3. The attempt at a solution Dont know how to do this problem at all. Im not understanding what the question is even asking for. I solved for the frequency that the observer in the car is hearing -- 242 Hz. Not sure how to figure out the question being asked.