Translate the following inference to logic notation: There is at least one x for which y_2 is a nurse if and only if y_2 is an office clerk. For all x, if y_2 were a nurse, then y_2 is playing tennis. For all x, y_2 is an office clerk if and only if y_2 will play tennis. Therefore there is at least one x for which y_2 is an office clerk if and only if y_2 will play tennis.
exists x: P(x) <-> Q(x). forall x: P(x) -> R(x). forall x: Q(x) <-> R(x). Therefore exists x: Q(x) <-> R(x).