What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: For all x_7, x_7 is a janitor. James is taking a plane if and only if Jennifer is working. For all x_7, if x_7 takes a plane, then x_7 is not a janitor.
If James takes a plane, then Jennifer is working can be inferred via the biconditional elimination rule. If Jennifer works, then James is taking a plane can be inferred via the biconditional elimination rule. For all x_7, x_7 will not take a plane can be inferred via the universal modus tollens rule.