Translate the following inference to logic notation: For all x, x_7 will not climb a mountain. There is at least one x for which x_7 will not take a plane or x_7 is sad. For all x, x_7 will take a plane or x_7 will sleep. For all x, if x_7 sleeps, then x_7 is climbing a mountain. Therefore there is at least one x for which x_7 is sad.
forall x: ~P(x). exists x: ~Q(x) or R(x). forall x: Q(x) or S(x). forall x: S(x) -> P(x). Therefore exists x: R(x).