I need to show that if p is an odd prime not equal to 5, then either or is divisible by 10. It was trivial to show that they were both divisible by 2, so all that's left is to show one of them must be divisible by 5. I tried this a couple of different ways. First, I tried to assume one was not divisible by 5, and prove that the other one was. I also multiplied them together and tried to show that was divisible by 5, since there is a theorem that states if p is prime and p divides ab, then p divides a or p divides b. However, I got stuck using both methods. Any help would be greatly appreciated.