Standing waves and microwave ovens

[pianogirl]

Homework Statement

With a wavelength of 12cm, how do I show that the microwave frequency is approx. 2.5GHz?

Homework Equations

v=f x lambda

The Attempt at a Solution

I'm confused about the wave speed bit...

 

[Delphi51]

Try putting the given numbers into the formula you wrote and see what happens!
We'll help you out if you show your work.