Translate the following inference to logic notation: For all x, if x_10 were sad, then x_10 is taking a plane. For all x, x_10 is sad if and only if x_10 will take a plane. For all x, if x_10 were sad, then x_10 is taking a plane. Therefore for all x, if x_10 were sad, then x_10 is taking a plane.
forall x: P(x) -> Q(x). forall x: P(x) <-> Q(x). forall x: P(x) -> Q(x). Therefore forall x: P(x) -> Q(x).