What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all y_1, y_1 is not a cashier. For all y_1, y_1 will listen to a song if and only if y_1 is a mechanic. For all y_1, y_1 is a cashier or y_1 will not listen to a song.
For all y_1, if y_1 listens to a song, then y_1 is a cashier. For all y_1, if y_1 listens to a song, then y_1 is a mechanic. For all y_1, if y_1 were a mechanic, then y_1 is listening to a song.