Question: 1. Prove, using contradiction or the contrapositive, that if the average age of four children is ten years old, then at least one child is at least ten years old.
2. Are the two graphs in Figure isomorphic? If so, exhibit the isomorphism. If not, find a property that should be preserved by isomorphism for which the two graphs differ. (A Geo Gebra file for Figure is available for your use at https://www.toroidalsnark.net/dmwdlinksfiles.html.)
