Translate the following inference to logic notation: For all x, if y were a janitor, then y is a cashier. James is not a janitor. For all x, y is a cashier if and only if y is a janitor. If it is overcast, then James is a cashier. Therefore it is not overcast.
forall x: P(x) -> Q(x). ~P(a). forall x: Q(x) <-> P(x). p -> Q(a). Therefore ~p.