Translate the following inference to logic notation: For all x, if x were a sailor, then x is a mechanic. There is at least one x for which x is a sailor if and only if x is a mechanic. Therefore there is at least one x for which if x were a mechanic, then x is a sailor.
forall x: P(x) -> Q(x). exists x: P(x) <-> Q(x). Therefore exists x: Q(x) -> P(x).