Discrete math using prime numbers

[colerelm]

How could I prove that (n choose k) / n is always an even number if n and k are relatively prime numbers?

All I've tried was plugging in some values for n and k and have seen that this does in fact work, but I don't know how to write a formal proof for it. What steps should I take in proving this?

Thanks

 

[daon2]

It isn't true. (2 choose 1)/2 = 1.