So I proved this was a relation, but I'm having real trouble identifying the elements of the relation. I'm not quite sure what I am supposed to do. Are the elements of the relation [(0,3)] all of the solutions to 0 = 3c? Any help would be great. I'm very confused on how to proceed. Any tips/websites you could offer me would help so much.
You are almost there, but it seems you may have sidetracked yourself by unnecessarily eliminating the $d$. The elements of $[(0,3)]$ are all pairs $(c,d)$ which are solutions to the equation $0d=3c$.