Consider the following premises. For all x_15, x_15 is not poor. Linda is fast if and only if Jennifer is a politician. Jennifer is a politician if and only if Susan is poor. Can we infer the following from them? If we can, name the inference rule being used: Linda is not fast.
 From the fact that for all x_15, x_15 is not poor we can infer that Susan is not poor via universal instantiation. From the fact that Jennifer is a politician if and only if Susan is poor, and that Susan is not poor we can infer that Jennifer is not a politician via biconditional elimination. From the fact that Linda is fast if and only if Jennifer is a politician we can infer that if Linda were fast, then Jennifer is a politician via biconditional elimination. Finally, from the fact that if Linda were fast, then Jennifer is a politician, and that Jennifer is not a politician we can infer that Linda is not fast via modus tollens. Therefore, the answer is yes.