Consider the following premises. Karen is a musician. Richard is a taxi driver if and only if Karen is a musician. Can we infer the following from them? If we can, name the inference rule being used: Richard is a taxi driver.
 From the fact that Richard is a taxi driver if and only if Karen is a musician we can infer that if Karen were a musician, then Richard is a taxi driver via biconditional elimination. Finally, from the fact that if Karen were a musician, then Richard is a taxi driver, and that Karen is a musician we can infer that Richard is a taxi driver via modus ponens. Therefore, the answer is yes.