Hi I have this problem, and I cant seem to get it. It is not for a grade just for study practice. Let me know if you can do it. Thanks...

Let G be a group, |G|= for a p a prime and (p,m) =1 and H G with |H|= . If K G with |K|= and HK = KH, then show K H.

Need to show K is a subgroup of H. Thanks again.