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: Karen is a nurse. If Linda makes tea, then Richard is poor. Mary is driving a car if and only if Richard is poor. If Mary drives a car, then Karen is not a nurse.
Mary is not driving a car can be inferred via the modus tollens rule. If Mary drives a car, then Richard is poor can be inferred via the biconditional elimination rule. If Richard were poor, then Mary is driving a car can be inferred via the biconditional elimination rule.