Consider the following premises. Jennifer is a cashier if and only if it is windy. Michael is driving a car or Joseph is a janitor. If Michael drives a car, then it is windy. If Joseph were a janitor, then Jennifer is a cashier. Can we infer the following from them? Jennifer is not a cashier.
 From the fact that Jennifer is a cashier if and only if it is windy we can infer that if it is windy, then Jennifer is a cashier. From the fact that if Michael drives a car, then it is windy, and that if it is windy, then Jennifer is a cashier we can infer that if Michael drives a car, then Jennifer is a cashier. Finally, from the fact that if Michael drives a car, then Jennifer is a cashier, that if Joseph were a janitor, then Jennifer is a cashier, and that Michael is driving a car or Joseph is a janitor we can infer that Jennifer is a cashier, which contradicts that Jennifer is not a cashier. Therefore, the answer is no.