Translate the following inference to logic notation: For all x, z_1 will read a book if and only if z_1 will play squash. For all x, if z_1 plays squash, then z_1 is reading a book. Therefore for all x, if z_1 plays squash, then z_1 is reading a book.
forall x: P(x) <-> Q(x). forall x: Q(x) -> P(x). Therefore forall x: Q(x) -> P(x).