Translate the following inference to logic notation: For all x, x_14 will play tennis if and only if x_14 is sad. For all x, if x_14 were sad, then x_14 is a taxi driver. There is at least one x for which x_14 will play tennis or x_14 is not a taxi driver. Therefore there is at least one x for which if x_14 were a taxi driver, then x_14 is playing tennis.
forall x: P(x) <-> Q(x). forall x: Q(x) -> R(x). exists x: P(x) or ~R(x). Therefore exists x: R(x) -> P(x).