Translate the following inference to logic notation: There is at least one x for which x_3 is a soldier if and only if x_3 is a sailor. For all x, x_3 will make tea if and only if x_3 is a sailor. For all x, x_3 is not a soldier. Therefore there is at least one x for which x_3 will not make tea.
exists x: P(x) <-> Q(x). forall x: R(x) <-> Q(x). forall x: ~P(x). Therefore exists x: ~R(x).