1. The problem statement, all variables and given/known data Didn't know what to title this one. I found it while I was doing some practice problems : http://gyazo.com/51a668d4db1a1638353a9de4b43d42ed 2. Relevant equations lcm(m,n) = k for some integer k. 3. The attempt at a solution I'm not really sure how to start this one. My guess is I want to argue with double inclusion? As in argue they're both subsets of each other. Any help would be great.