Translate the following inference to logic notation: For all x, x will drink water if and only if x will write a letter. For all x, x will drink water if and only if x will write a letter. Therefore for all x, x will write a letter if and only if x will drink water.
forall x: P(x) <-> Q(x). forall x: P(x) <-> Q(x). Therefore forall x: Q(x) <-> P(x).