Consider the following premises. For all x_11, x_11 is a cashier if and only if x_11 is a janitor. Charles is not a janitor. Barbara is making tea. Can we infer the following from them? If we can, name the inference rule being used: Charles is not a cashier and Barbara is making tea.
 From the fact that for all x_11, x_11 is a cashier if and only if x_11 is a janitor we can infer that Charles is a cashier if and only if Charles is a janitor via universal instantiation. From the fact that Charles is a cashier if and only if Charles is a janitor, and that Charles is not a janitor we can infer that Charles is not a cashier via biconditional elimination. Finally, from the fact that Charles is not a cashier, and that Barbara is making tea we can infer that Charles is not a cashier and Barbara is making tea via conjunction. Therefore, the answer is yes.