What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? David is reading a book if and only if John is driving a car. David is not reading a book. It is sunny.
David is not reading a book and it is sunny. It is sunny and David is not reading a book. If David reads a book, then John is driving a car. If John drives a car, then David is reading a book. John is not driving a car.