Translate the following inference to logic notation: For all x, y is a nurse or y is not a janitor. For all x, y is a nurse if and only if y is a janitor. Therefore for all x, if y were a janitor, then y is a nurse.
forall x: P(x) or ~Q(x). forall x: P(x) <-> Q(x). Therefore forall x: Q(x) -> P(x).