What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all y, if y drives a car, then y is not an office clerk. For all y, y is a doctor if and only if y will drive a car. For all y, y is an office clerk. If John listens to a song, then Charles is a doctor.
For all y, y will not drive a car. For all y, if y were a doctor, then y is driving a car. For all y, if y drives a car, then y is a doctor.