Translate the following inference to logic notation: There is at least one x for which x_9 is an electrician if and only if x_9 will drive a car. For all x, if x_9 takes a plane, then x_9 is an electrician. For all x, if x_9 drives a car, then x_9 is taking a plane. Therefore there is at least one x for which x_9 is an electrician if and only if x_9 will take a plane.
exists x: P(x) <-> Q(x). forall x: R(x) -> P(x). forall x: Q(x) -> R(x). Therefore exists x: P(x) <-> R(x).