Translate the following inference to logic notation: For all x, if x_9 were a lawyer, then x_9 is an electrician. For all x, if x_9 were an electrician, then x_9 is a writer. For all x, x_9 is a lawyer or x_9 will not play squash. For all x, if x_9 were a writer, then x_9 is playing squash. Therefore for all x, x_9 is a writer if and only if x_9 is a lawyer.
forall x: P(x) -> Q(x). forall x: Q(x) -> R(x). forall x: P(x) or ~S(x). forall x: R(x) -> S(x). Therefore forall x: R(x) <-> P(x).