Translate the following inference to logic notation: For all x, if x_23 plays tennis, then x_23 is working. David is taking a plane. For all x, if x_23 takes a plane, then x_23 is playing tennis. For all x, if x_23 works, then x_23 is playing tennis. Therefore there is at least one x for which x_23 will work.
forall x: P(x) -> Q(x). R(a). forall x: R(x) -> P(x). forall x: Q(x) -> P(x). Therefore exists x: Q(x).