Translate the following inference to logic notation: For all x, if x_15 goes running, then x_15 is rich. For all x, x_15 is not rich. For all x, x_15 will go running if and only if x_15 will drink water. There is at least one x for which x_15 will drink water. Therefore there is at least one x for which x_15 will write a letter.
forall x: P(x) -> Q(x). forall x: ~Q(x). forall x: P(x) <-> R(x). exists x: R(x). Therefore exists x: S(x).