Translate the following inference to logic notation: If Susan sleeps, then it is late. It is not late. If Richard were a janitor, then Susan is listening to a song. For all x, if x_15 listens to a song, then x_15 is sleeping. Therefore Richard is not a janitor.
P(a) -> p. ~p. q -> Q(a). forall x: Q(x) -> P(x). Therefore ~q.