Consider the following premises. For all y_1, y_1 will write a letter. Thomas is a musician. Can we infer the following from them? Charles is writing a letter and Thomas is a musician.
 From the fact that for all y_1, y_1 will write a letter we can infer that Charles is writing a letter. Finally, from the fact that Charles is writing a letter, and that Thomas is a musician we can infer that Charles is writing a letter and Thomas is a musician. Therefore, the answer is yes.