Translate the following inference to logic notation: For all x, x_3 will take a plane if and only if x_3 is a taxi driver. There is at least one x for which x_3 will take a plane or x_3 is not a taxi driver. Therefore there is at least one x for which if x_3 were a taxi driver, then x_3 is taking a plane.
forall x: P(x) <-> Q(x). exists x: P(x) or ~Q(x). Therefore exists x: Q(x) -> P(x).