Consider the following premises. For all x_8, if x_8 were a server, then x_8 is a cashier. For all x_8, if x_8 were a janitor, then x_8 is a server. For all x_8, x_8 is a janitor if and only if x_8 is a cashier. Can we infer the following from them? If we can, name the inference rule being used: If John were a cashier, then John is a janitor.
 From the fact that for all x_8, if x_8 were a janitor, then x_8 is a server, and that for all x_8, if x_8 were a server, then x_8 is a cashier we can infer that for all x_8, if x_8 were a janitor, then x_8 is a cashier via universal transitivity. From the fact that for all x_8, x_8 is a janitor if and only if x_8 is a cashier we can infer that for all x_8, if x_8 were a cashier, then x_8 is a janitor via universal biconditional elimination. From the fact that for all x_8, if x_8 were a janitor, then x_8 is a cashier, and that for all x_8, if x_8 were a cashier, then x_8 is a janitor we can infer that for all x_8, x_8 is a janitor if and only if x_8 is a cashier via universal biconditional introduction. From the fact that for all x_8, x_8 is a janitor if and only if x_8 is a cashier we can infer that John is a janitor if and only if John is a cashier via universal instantiation. Finally, from the fact that John is a janitor if and only if John is a cashier we can infer that if John were a cashier, then John is a janitor via biconditional elimination. Therefore, the answer is yes.