Prove the following statements Hint: Use Contrapositive and DeMorgan's laws to reduce each line to the statements in problem II. Use A for ∀,"For all" and E for ∃,"There exists" a.) ∃xC(x) + ∃xB(x) <=> ∃x[C(x) + B(x)] show <=> to ∀xP(x)* ∀xQ(x)<=> ∀x [P(x) * Q(x)]