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