Translate the following inference to logic notation: For all x, x_3 is not a carpenter. For all x, x_3 will write a letter if and only if x_3 is a server. For all x, if x_3 were a carpenter, then x_3 is writing a letter. There is at least one x for which if x_3 writes a letter, then x_3 is a carpenter. Therefore there is at least one x for which x_3 is not a server.
forall x: ~P(x). forall x: Q(x) <-> R(x). forall x: P(x) -> Q(x). exists x: Q(x) -> P(x). Therefore exists x: ~R(x).