I am correcting a test but need the formulas

[Petie]

13. A microwave oven warms food using electromagnetic waves with a frequency of 8.5x10^9 Hz. What is the wavelength of these microwaves in nm?

14. Light from a distant planet reaches Earth in 6.5 years. How far from Earth is this planet in meters?

16. What is the frequency of light from Mr. Teacher's laser pointer if it produces a coherent beam of 552 nm light?

I can't remember the mirror stuff at the moment but I can help with these three.

13 and 16 both use the frequency = wavelength / speed of light - just plug in and solve.
14 uses distance = time * speed of light but make sure you balance your units. 6.5 years won't directly match up against the unit for the speed of light.

A standard estimate of the speed of light is 300,000,000 m/s which should suffice unless you're supposed to use a more specific value.