1.Prove: for all a ϵ Z, for all b ϵ Z if a│b then aČ│bČ

2.Prove: for all n ϵ Z, n is add if and only if nČ is odd.

3.using the definition of equal sets and the definition of subset, prove this

form of DeMorgan's Law:____ _ _

If A and B are sets then AUB=A∩B

Please help!!!!