Consider the following premises. For all x_19, x_19 is not a cashier. If James were a scientist, then Barbara is a cashier. Joseph is making tea if and only if James is a scientist. Can we infer the following from them? If we can, name the inference rule being used: Joseph is making tea.
 From the fact that for all x_19, x_19 is not a cashier we can infer that Barbara is not a cashier via universal instantiation. From the fact that if James were a scientist, then Barbara is a cashier, and that Barbara is not a cashier we can infer that James is not a scientist via modus tollens. Finally, from the fact that Joseph is making tea if and only if James is a scientist, and that James is not a scientist we can infer that Joseph is not making tea via biconditional elimination, which contradicts that Joseph is making tea. Therefore, the answer is no.