Translate the following inference to logic notation: There is at least one x for which if x_7 were poor, then x_7 is sad. For all x, x_7 is a sailor and x_7 will take a plane. For all x, if x_7 were sad, then x_7 is not a sailor. Therefore there is at least one x for which x_7 is not poor.
exists x: P(x) -> Q(x). forall x: R(x) and S(x). forall x: Q(x) -> ~R(x). Therefore exists x: ~P(x).