Translate the following inference to logic notation: For all x, x is happy if and only if x is an office clerk. There is at least one x for which x is an office clerk or x will play tennis. For all x, x is not happy. Therefore there is at least one x for which x will play tennis.
forall x: P(x) <-> Q(x). exists x: Q(x) or R(x). forall x: ~P(x). Therefore exists x: R(x).