Translate the following inference to logic notation: There is at least one x for which x_7 is not a janitor. For all x, x_7 is not a mechanic. For all x, x_7 is a mechanic. Therefore there is at least one x for which x_7 is a nurse.
exists x: ~P(x). forall x: ~Q(x). forall x: Q(x). Therefore exists x: R(x).