Translate the following inference to logic notation: For all x, z_4 is not sad or z_4 is a writer. For all x, z_4 is sad. For all x, z_4 is not a writer. There is at least one x for which z_4 will not sleep or z_4 will drink water. Therefore there is at least one x for which z_4 will drink water.
forall x: ~P(x) or Q(x). forall x: P(x). forall x: ~Q(x). exists x: ~R(x) or S(x). Therefore exists x: S(x).