Consider the following premises. David is climbing a mountain. If Karen were a bartender, then Richard is fast. Richard is not fast. Karen is a bartender if and only if James is a sailor. Can we infer the following from them? If we can, name the inference rule being used: James is a sailor.
 From the fact that if Karen were a bartender, then Richard is fast, and that Richard is not fast we can infer that Karen is not a bartender via modus tollens. Finally, from the fact that Karen is a bartender if and only if James is a sailor, and that Karen is not a bartender we can infer that James is not a sailor via biconditional elimination, which contradicts that James is a sailor. Therefore, the answer is no.