Translate the following inference to logic notation: For all x, if z makes tea, then z is an electrician. For all x, if z were an electrician, then z is making tea. For all x, z is an electrician or z will not make tea. Therefore for all x, z is an electrician if and only if z will make tea.
forall x: P(x) -> Q(x). forall x: Q(x) -> P(x). forall x: Q(x) or ~P(x). Therefore forall x: Q(x) <-> P(x).