Relations on the set of natural numbers

Question

I was working on a problem asking me whether on not the relation is symmetric, reflexive, or transitive? The defined relation R on N by aRb if a/b is an element of N. I found that it is reflexive. Not transitive and not symmetric. The counter example for symmetry was easy but I am getting caught off by finding numbers to prove a/b, b/c does not equal a/c some further explanation on why I can't find a counter example would help.