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: If Susan were excited, then Joseph is not cooking. Joseph is cooking. For all x_7, x_7 is excited if and only if x_7 will drive a car.
Susan is not excited can be inferred via the modus tollens rule. For all x_7, if x_7 were excited, then x_7 is driving a car can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 drives a car, then x_7 is excited can be inferred via the universal biconditional elimination rule.