Translate the following inference to logic notation: There is at least one x for which x_5 is sad if and only if x_5 will drink water. For all x, x_5 will not play squash. For all x, if x_5 drives a car, then x_5 is playing squash. For all x, if x_5 drinks water, then x_5 is driving a car. Therefore there is at least one x for which x_5 is not sad.
exists x: P(x) <-> Q(x). forall x: ~R(x). forall x: S(x) -> R(x). forall x: Q(x) -> S(x). Therefore exists x: ~P(x).