Consider the following premises. If Karen were rich, then it is snowing. For all x_10, x_10 will drink water or x_10 is rich. If it snows, then Karen is drinking water. If Karen drinks water, then it is snowing. 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_10, x_10 will drink water or x_10 is rich we can infer that Karen is drinking water or Karen is rich via universal instantiation. From the fact that if Karen drinks water, then it is snowing, and that if it snows, then Karen is drinking water we can infer that Karen is drinking water if and only if it is snowing via biconditional introduction. From the fact that Karen is drinking water if and only if it is snowing we can infer that if Karen drinks water, then it is snowing via biconditional elimination. Finally, from the fact that if Karen drinks water, then it is snowing, that if Karen were rich, then it is snowing, and that Karen is drinking water or Karen is rich we can infer that it is snowing via disjunction elimination. Therefore, the answer is yes.