Translate the following inference to logic notation: For all x, x_3 is a cashier if and only if x_3 will play tennis. There is at least one x for which if x_3 reads a book, then x_3 is a cashier. Therefore there is at least one x for which if x_3 reads a book, then x_3 is playing tennis.
forall x: P(x) <-> Q(x). exists x: R(x) -> P(x). Therefore exists x: R(x) -> Q(x).