My apologies, I put the wrong question (I had v = f/λ when it should be v= fλ); I fixed this up now.
But by your statement would be the last option I suggested? λ = (speed of sound + speed of wind + speed of source)/(new frequency)?
Homework Statement
A listener L hears the siren from a moving police car ,S, which is moving away from the listener with a speed of v = 20.0 m/s. The listener is moving at 10.0 m/s towards the car. There is a wind blowing with a speed of v(wind)= 10.0 m/s from S to L. The siren is emitting...