"The set of rational number is closed under division. -- TRUE OR FALSE" I think this is false, but simply cause I read it in my text book (or mis-read it if I am wrong).
If then what can you say about ?
What happens if that ratio is not rational?
Good grief, if that is true, what do you know? What do you know about rational numbers? Are you trying to get a completely solved, ready to turn in solution?