Translate the following inference to logic notation: For all x, x_7 is sad or x_7 is an electrician. For all x, if x_7 were an electrician, then x_7 is a writer. For all x, x_7 is sad if and only if x_7 is a writer. There is at least one x for which if x_7 plays squash, then x_7 is not a writer. Therefore there is at least one x for which x_7 will not play squash.
forall x: P(x) or Q(x). forall x: Q(x) -> R(x). forall x: P(x) <-> R(x). exists x: S(x) -> ~R(x). Therefore exists x: ~S(x).