Translate the following inference to logic notation: For all x, z is a sailor if and only if z is a mechanic. For all x, z is a sailor or z is not an office clerk. Therefore for all x, if z were an office clerk, then z is a mechanic.
forall x: P(x) <-> Q(x). forall x: P(x) or ~R(x). Therefore forall x: R(x) -> Q(x).