Consider the following premises. For all x_7, x_7 is sad or x_7 is not a musician. Thomas is not sad. Can we infer the following from them? If we can, name the inference rule being used: Thomas is not a musician.
 From the fact that for all x_7, x_7 is sad or x_7 is not a musician we can infer that for all x_7, if x_7 were a musician, then x_7 is sad via universal rewriting. From the fact that for all x_7, if x_7 were a musician, then x_7 is sad we can infer that if Thomas were a musician, then Thomas is sad via universal instantiation. Finally, from the fact that if Thomas were a musician, then Thomas is sad, and that Thomas is not sad we can infer that Thomas is not a musician via modus tollens. Therefore, the answer is yes.