Translate the following inference to logic notation: For all x, z is a janitor if and only if z is a scientist. For all x, if z were a janitor, then z is a writer. For all x, z is a scientist or z is not a writer. Therefore for all x, z is a scientist if and only if z is a writer.
forall x: P(x) <-> Q(x). forall x: P(x) -> R(x). forall x: Q(x) or ~R(x). Therefore forall x: Q(x) <-> R(x).