Translate the following inference to logic notation: For all x, x_17 is a cashier if and only if x_17 will sleep. For all x, if x_17 reads a book, then x_17 is playing squash. There is at least one x for which x_17 will read a book. For all x, if x_17 plays squash, then x_17 is sleeping. Therefore there is at least one x for which x_17 is a cashier.
forall x: P(x) <-> Q(x). forall x: R(x) -> S(x). exists x: R(x). forall x: S(x) -> Q(x). Therefore exists x: P(x).