I know which equations to use for solving Doppler Effect problems, so figuring out which is the observer and which is the source and which is moving or stationary is not the problem, the problem I am having is in solving the actual formulas...... This question might belong in the math help section but I thought it was best to post this in the physics area because it does deal with a physics topic. Anyway, I attached the equations as graphics (maybe somebody knows how to LATEX these?). I am looking for some help in rearranging these equations to solve for each of the variables, V,Vs,Vo,Fo,Fs. Can somebody please help me arrange the formula where I can solve for Vs??