Consider the following premises. It is cloudy if and only if it is windy. David is not poor. It is not windy. David is poor if and only if it is sunny. Can we infer the following from them? If we can, name the inference rule being used: It is not sunny.
 From the fact that it is cloudy if and only if it is windy, and that it is not windy we can infer that it is not cloudy via biconditional elimination. Finally, from the fact that David is poor if and only if it is sunny, and that David is not poor we can infer that it is not sunny via biconditional elimination. Therefore, the answer is yes.