Translate the following inference to logic notation: For all x, x_9 will take a plane if and only if x_9 is a janitor. For all x, x_9 is not a janitor. For all x, x_9 will take a plane or x will play tennis. Therefore there is at least one x for which x will play tennis.
forall x: P(x) <-> Q(x). forall x: ~Q(x). forall x: P(x) or R(x). Therefore exists x: R(x).