A sound wave has a wavelength of 0.450 meters. If its speed in cold air is 330 meters/second, what is the wave's frequency?

Most of the information's required are already given in the question. Based on those information's the answer can be easily deduced.

Wavelength of the sound wave = 0.450 meters

Speed of the sound wave = 330 meters per second

We already know

v=f λ

330 = f * 0.450

f = 330/0.450

= 733.33 hertz

So the frequency of the wave is 733.33 hertz