Consider the following premises. For all x_7, x_7 will work if and only if x_7 will climb a mountain. For all x_7, x_7 will climb a mountain or x_7 will listen to a song. For all x_7, x_7 will not work. Can we infer the following from them? John is listening to a song.
 From the fact that for all x_7, x_7 will work if and only if x_7 will climb a mountain, and that for all x_7, x_7 will not work we can infer that for all x_7, x_7 will not climb a mountain. From the fact that for all x_7, x_7 will climb a mountain or x_7 will listen to a song, and that for all x_7, x_7 will not climb a mountain we can infer that for all x_7, x_7 will listen to a song. Finally, from the fact that for all x_7, x_7 will listen to a song we can infer that John is listening to a song. Therefore, the answer is yes.