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