Igot the right answer for this question (pretty sure i guessed or just asked me teacher the answer? ) but can someone explain how i got that answer (like the process of figuring it out) : )

How you got the

-- Either you guessed, or else you asked somebody else and they gave you the answer.  It really doesn't matter.  As you can see, whichever it was, you didn't learn anything in the process.

The helpful and correct way to solve the problem:

-- For any wave, Speed = (frequency) x (wavelength)

Whenever you're dealing with waves, and you know any two of those three quantities, you can always use this formula to calculate the quantity you don't know.

This problem GIVES you the speed and the wavelength.  USE this formula to calculate the frequency.

b.

hope this : )