chemistry help please?

[Answer Man]

Calculate the wavelength (in nm) of a photon emitted from a hydrogen atom when its electron drops from the n=3 state to the n=1 state.

this is a question m=on my chemistry study guide and i am lost. we have to show our work in order to get credit for completing the study guide. Please help if you can

 

[Daniel N]

the wavelength should increase when you drop from 3 to 1. You use the rayburg equation.