Translate the following inference to logic notation: There is at least one x for which x_10 is an electrician if and only if x_10 is a cashier. For all x, if x_10 were an electrician, then x_10 is a nurse. For all x, x_10 is a cashier. Therefore there is at least one x for which x_10 is a nurse.
exists x: P(x) <-> Q(x). forall x: P(x) -> R(x). forall x: Q(x). Therefore exists x: R(x).