Translate the following inference to logic notation: For all x, x_7 is not happy. For all x, x_7 will work if and only if x_7 is an electrician. For all x, x_7 is happy or x_7 will work. Therefore for all x, x_7 is an electrician.
forall x: ~P(x). forall x: Q(x) <-> R(x). forall x: P(x) or Q(x). Therefore forall x: R(x).