What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_4, x_4 will listen to a song if and only if x_4 is a taxi driver. For all x_4, x_4 is a sailor. For all x_4, x_4 will make tea or x_4 is a taxi driver. There is at least one x_4 for which if x_4 makes tea, then x_4 is listening to a song.
For all x_4, if x_4 listens to a song, then x_4 is a taxi driver. For all x_4, if x_4 were a taxi driver, then x_4 is listening to a song.