A very important equation that we have learned is V=fh. The V is the velocity. The f is the frequency. And the h (which looks like a fancy backward h) is te wave length this is called lamda. The velocity of air in STP is 331m/s. How we applied this equation is questions would be asking you to find something in the equation. So for example if you were asked to find lamda given the velocity, you would plug in what you have and solve. Like if the wave was traveling at a speed of 10m/s and the frequency is 5 hz. You would divide 10\5 to get the wavelength of 2 meters.