Consider the following premises. For all x_14, if x_14 plays squash, then x_14 is writing a letter. For all x_14, if x_14 climbs a mountain, then x_14 is a musician. For all x_14, if x_14 writes a letter, then x_14 is playing squash. There is at least one x_14 for which x_14 will play squash if and only if x_14 will climb a mountain. Can we infer the following from them? There is at least one x_14 for which if x_14 writes a letter, then x_14 is a musician.
 From the fact that there is at least one x_14 for which x_14 will play squash if and only if x_14 will climb a mountain we can infer that there is at least one x_14 for which if x_14 plays squash, then x_14 is climbing a mountain. From the fact that there is at least one x_14 for which if x_14 plays squash, then x_14 is climbing a mountain, and that for all x_14, if x_14 climbs a mountain, then x_14 is a musician we can infer that there is at least one x_14 for which if x_14 plays squash, then x_14 is a musician. From the fact that for all x_14, if x_14 plays squash, then x_14 is writing a letter, and that for all x_14, if x_14 writes a letter, then x_14 is playing squash we can infer that for all x_14, x_14 will play squash if and only if x_14 will write a letter. From the fact that for all x_14, x_14 will play squash if and only if x_14 will write a letter we can infer that for all x_14, if x_14 writes a letter, then x_14 is playing squash. Finally, from the fact that for all x_14, if x_14 writes a letter, then x_14 is playing squash, and that there is at least one x_14 for which if x_14 plays squash, then x_14 is a musician we can infer that there is at least one x_14 for which if x_14 writes a letter, then x_14 is a musician. Therefore, the answer is yes.