Consider the following premises. It is windy if and only if Susan is a politician. If it is windy, then Susan is a politician. It is not windy. William is poor. Can we infer the following from them? If we can, name the inference rule being used: Susan is not a politician and William is poor.
 From the fact that it is windy if and only if Susan is a politician we can infer that if Susan were a politician, then it is windy via biconditional elimination. From the fact that if it is windy, then Susan is a politician, and that if Susan were a politician, then it is windy we can infer that it is windy if and only if Susan is a politician via biconditional introduction. From the fact that it is windy if and only if Susan is a politician, and that it is not windy we can infer that Susan is not a politician via biconditional elimination. Finally, from the fact that Susan is not a politician, and that William is poor we can infer that Susan is not a politician and William is poor via conjunction. Therefore, the answer is yes.