Stupid little question. Just wanted you to check my work. This was the quickest way I saw to do it, but i'm not convinced it's the best way, or even valid at all.
Prove that if , then there is a solution (for ) to the congruence .
Assume . Then for . We want to show that there exists an such that , for (since this would mean
). Rearranging our first equation we have . It suffices to take
does that work?