Consider the following premises. If Robert were sad, then Joseph is not sleeping. Joseph is sleeping. For all z, z is sad or z will listen to a song. Can we infer the following from them? If we can, name the inference rule being used: Robert is listening to a song.
 From the fact that for all z, z is sad or z will listen to a song we can infer that Robert is sad or Robert is listening to a song via universal instantiation. From the fact that if Robert were sad, then Joseph is not sleeping, and that Joseph is sleeping we can infer that Robert is not sad via modus tollens. Finally, from the fact that Robert is sad or Robert is listening to a song, and that Robert is not sad we can infer that Robert is listening to a song via disjunctive syllogism. Therefore, the answer is yes.