Determine for each of the following truth functional statements whether it is a tautology, a contradiction, or contingent. You can use a truth table to determine their status or a shorter method but whatever method you choose, show enough reasoning to confirm your verdict.
If not (W only if not Z) then (Z or not W)
not [(not G if M) and not (if not G then M)]
If (A if and only if not B) then not (B if not A)