Consider the following premises. Jennifer is playing a game if and only if Jennifer is not climbing a mountain. For all x_23, x_23 is poor. If Jennifer climbs a mountain, then Robert is not poor. Can we infer the following from them? If we can, name the inference rule being used: Jennifer is playing a game.
 From the fact that for all x_23, x_23 is poor we can infer that Robert is poor via universal instantiation. From the fact that if Jennifer climbs a mountain, then Robert is not poor, and that Robert is poor we can infer that Jennifer is not climbing a mountain via modus tollens. From the fact that Jennifer is playing a game if and only if Jennifer is not climbing a mountain we can infer that if Jennifer doesn't climb a mountain, then Jennifer is playing a game via biconditional elimination. Finally, from the fact that if Jennifer doesn't climb a mountain, then Jennifer is playing a game, and that Jennifer is not climbing a mountain we can infer that Jennifer is playing a game via modus ponens. Therefore, the answer is yes.