Translate the following inference to logic notation: Karen is working if and only if Richard is a mechanic. For all x, if x_10 works, then x_10 is happy. For all x, x_10 is not happy. For all x, if x_10 were happy, then x_10 is working. Therefore Richard is not a mechanic.
P(a) <-> p. forall x: P(x) -> Q(x). forall x: ~Q(x). forall x: Q(x) -> P(x). Therefore ~p.