Consider the following premises. If Sarah drives a car, then Charles is a cashier. For all y, if y were a musician, then y is a cashier. Charles is not a musician. For all y, y is a cashier if and only if y is a musician. Can we infer the following from them? If we can, name the inference rule being used: Sarah is driving a car.
 From the fact that for all y, y is a cashier if and only if y is a musician we can infer that for all y, if y were a cashier, then y is a musician via universal biconditional elimination. From the fact that for all y, if y were a musician, then y is a cashier, and that for all y, if y were a cashier, then y is a musician we can infer that for all y, y is a musician if and only if y is a cashier via universal biconditional introduction. From the fact that for all y, y is a musician if and only if y is a cashier we can infer that Charles is a musician if and only if Charles is a cashier via universal instantiation. From the fact that Charles is a musician if and only if Charles is a cashier, and that Charles is not a musician we can infer that Charles is not a cashier via biconditional elimination. Finally, from the fact that if Sarah drives a car, then Charles is a cashier, and that Charles is not a cashier we can infer that Sarah is not driving a car via modus tollens, which contradicts that Sarah is driving a car. Therefore, the answer is no.