Translate the following inference to logic notation: For all x, if x_6 climbs a mountain, then x_6 is a nurse. For all x, x_6 is not a nurse. For all x, x_6 will climb a mountain if and only if x_6 will write a letter. For all x, if x_6 climbs a mountain, then x_6 is writing a letter. Therefore for all x, x_6 will not write a letter.
forall x: P(x) -> Q(x). forall x: ~Q(x). forall x: P(x) <-> R(x). forall x: P(x) -> R(x). Therefore forall x: ~R(x).