Translate the following inference to logic notation: For all x, x_9 will work if and only if x_9 will take a plane. There is at least one x for which x_9 will take a plane if and only if x_9 is curious. Therefore there is at least one x for which if x_9 were curious, then x_9 is working.
forall x: P(x) <-> Q(x). exists x: Q(x) <-> R(x). Therefore exists x: R(x) -> P(x).