I've spent a long time thinking by myself and I can't figure out how to proceed:
Is there a simple graph G with 60 edges such that it's complementary graph GC has 52 edges?
Also, on wikipedia I don't get this entry :
"Let G = (V, E) be a simple graph and let K consist of all 2-element subsets of V. Then H = (V, K \ E) is the complement of G."
What is K supposed to be? I don't get what are 2-element subsets of V. I've drawn a simple graph G(3,3) : triangle, which has a GC(3,k/3) : Three isolated vertices. So k should be equal to zero???