Respuesta :
The correct answer for the question that is being presented above is this one: "b. 22 hz and 42 hz." If 20 beats are produced within one second the frequencies that could possibly be held by two sound waves traveling through a medium along a common pants at the same time are b. 22 hz and 42 hz
The frequency of the beat is the difference in the two frequencies involved, so you need to check which pairs of frequency have a difference of 20 Hz.
so Answer is 22 and 42