Consider the following premises. If Robert takes a plane, then Susan is not fast. For all y, y is fast. If Robert doesn't take a plane, then James is writing a letter. Can we infer the following from them? If we can, name the inference rule being used: James is writing a letter.
 From the fact that for all y, y is fast we can infer that Susan is fast via universal instantiation. From the fact that if Robert takes a plane, then Susan is not fast, and that Susan is fast we can infer that Robert is not taking a plane via modus tollens. Finally, from the fact that if Robert doesn't take a plane, then James is writing a letter, and that Robert is not taking a plane we can infer that James is writing a letter via modus ponens. Therefore, the answer is yes.