Consider the following premises. For all x_8, x_8 is a server if and only if x_8 will drink water. For all x_8, x_8 is not a server. If it snows, then Mary is drinking water. Can we infer the following from them? If we can, name the inference rule being used: It is snowing.
 From the fact that for all x_8, x_8 is a server if and only if x_8 will drink water, and that for all x_8, x_8 is not a server we can infer that for all x_8, x_8 will not drink water via universal biconditional elimination. From the fact that for all x_8, x_8 will not drink water we can infer that Mary is not drinking water via universal instantiation. Finally, from the fact that if it snows, then Mary is drinking water, and that Mary is not drinking water we can infer that it is not snowing via modus tollens, which contradicts that It is snowing. Therefore, the answer is no.