7.4, due on 3/7

1.  Most of the ideas made sense.

2.  When I read the definition of a group I thought it was pretty close to some of the axioms of a ring so Theorem 7.1 was straightforward.  Corollary 7.3 was a clear corollary and it made sense.  Theorem 7.4 made sense and the proof probably isn't too rough.