Consider the following premises. Charles is playing tennis if and only if John is making tea. For all x_2, x_2 will not climb a mountain. If John makes tea, then Sarah is climbing a mountain. Can we infer the following from them? If we can, name the inference rule being used: Charles is playing tennis.
 From the fact that for all x_2, x_2 will not climb a mountain we can infer that Sarah is not climbing a mountain via universal instantiation. From the fact that if John makes tea, then Sarah is climbing a mountain, and that Sarah is not climbing a mountain we can infer that John is not making tea via modus tollens. Finally, from the fact that Charles is playing tennis if and only if John is making tea, and that John is not making tea we can infer that Charles is not playing tennis via biconditional elimination, which contradicts that Charles is playing tennis. Therefore, the answer is no.