Translate the following inference to logic notation: For all x, x_3 is not happy. For all x, if x_3 takes a plane, then x_3 is happy. There is at least one x for which if x_3 were a mechanic, then x_3 is taking a plane. For all x, if x_3 were happy, then x_3 is taking a plane. Therefore there is at least one x for which x_3 is not a mechanic.
forall x: ~P(x). forall x: Q(x) -> P(x). exists x: R(x) -> Q(x). forall x: P(x) -> Q(x). Therefore exists x: ~R(x).