Translate the following inference to logic notation: For all x, x_9 is an electrician or x_9 will make tea. For all x, if x_9 makes tea, then x_9 is a sailor. There is at least one x for which x_9 is a mechanic if and only if x_9 is an electrician. For all x, if x_9 were a sailor, then x_9 is a mechanic. Therefore there is at least one x for which x_9 is a mechanic.
forall x: P(x) or Q(x). forall x: Q(x) -> R(x). exists x: S(x) <-> P(x). forall x: R(x) -> S(x). Therefore exists x: S(x).