Consider the following premises. For all x_19, if x_19 plays squash, then x_19 is a writer. If James climbs a mountain, then it is cold. Jennifer is not a writer. It is cold if and only if Jennifer is playing squash. Can we infer the following from them? If we can, name the inference rule being used: James is not climbing a mountain.
 From the fact that for all x_19, if x_19 plays squash, then x_19 is a writer we can infer that if Jennifer plays squash, then Jennifer is a writer via universal instantiation. From the fact that if Jennifer plays squash, then Jennifer is a writer, and that Jennifer is not a writer we can infer that Jennifer is not playing squash via modus tollens. From the fact that it is cold if and only if Jennifer is playing squash, and that Jennifer is not playing squash we can infer that it is not cold via biconditional elimination. Finally, from the fact that if James climbs a mountain, then it is cold, and that it is not cold we can infer that James is not climbing a mountain via modus tollens. Therefore, the answer is yes.