What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? If it is late, then Jessica is a janitor. It is not late. If Jessica were a janitor, then it is late. If James takes a plane, then Jessica is a janitor.
Jessica is not a janitor. If James takes a plane, then it is late. It is late if and only if Jessica is a janitor. Jessica is a janitor if and only if it is late.