Translate the following inference to logic notation: For all x, x_9 will not write a letter. For all x, x_9 will read a book if and only if x_9 will play tennis. For all x, x_9 will play tennis if and only if x_9 will take a plane. There is at least one x for which if x_9 takes a plane, then x_9 is writing a letter. Therefore there is at least one x for which x_9 will not read a book.
forall x: ~P(x). forall x: Q(x) <-> R(x). forall x: R(x) <-> S(x). exists x: S(x) -> P(x). Therefore exists x: ~Q(x).