Translate the following inference to logic notation: For all x, if y_3 were a musician, then y_3 is writing a letter. For all x, y_3 will write a letter or y_3 is an office clerk. For all x, if y_3 were an office clerk, then y_3 is a musician. There is at least one x for which if y_3 writes a letter, then y_3 is a musician. Therefore there is at least one x for which y_3 is a musician.
forall x: P(x) -> Q(x). forall x: Q(x) or R(x). forall x: R(x) -> P(x). exists x: Q(x) -> P(x). Therefore exists x: P(x).