Translate the following inference to logic notation: Michael is not fast. For all x, x_20 is a janitor if and only if x_20 is fast. Charles is playing tennis. If Michael were not a janitor, then it is overcast. Therefore Charles is playing tennis and it is overcast.
~P(a). forall x: Q(x) <-> P(x). p. ~Q(a) -> q. Therefore p and q.