Translate the following inference to logic notation: Richard is not a sailor. Richard is a politician if and only if Susan is listening to a song. Richard is a politician if and only if Richard is a sailor. For all x, x_3 will listen to a song if and only if x_3 will write a letter. Therefore Susan is not writing a letter.
~p. q <-> P(a). q <-> p. forall x: P(x) <-> Q(x). Therefore ~Q(a).