Translate the following inference to logic notation: For all x, y_2 is a cashier if and only if y_2 will play tennis. For all x, if y_2 plays tennis, then y_2 is taking a plane. There is at least one x for which y_2 will not take a plane. Therefore there is at least one x for which y_2 is not a cashier.
forall x: P(x) <-> Q(x). forall x: Q(x) -> R(x). exists x: ~R(x). Therefore exists x: ~P(x).