Consider the following premises. It is not sunny. David is cooking if and only if it is snowing. It is sunny if and only if Richard is climbing a mountain. David is not cooking. Can we infer the following from them? If we can, name the inference rule being used: Richard is not climbing a mountain and it is not snowing.
 From the fact that David is cooking if and only if it is snowing, and that David is not cooking we can infer that it is not snowing via biconditional elimination. From the fact that it is sunny if and only if Richard is climbing a mountain, and that it is not sunny we can infer that Richard is not climbing a mountain via biconditional elimination. Finally, from the fact that Richard is not climbing a mountain, and that it is not snowing we can infer that Richard is not climbing a mountain and it is not snowing via conjunction. Therefore, the answer is yes.