Consider the following premises. For all x_9, if x_9 were a writer, then x_9 is a mechanic. There is at least one x_9 for which x_9 will play squash if and only if x_9 is a mechanic. For all x_9, x_9 is a writer. Can we infer the following from them? For all x_9, x_9 will not play squash.
 From the fact that there is at least one x_9 for which x_9 will play squash if and only if x_9 is a mechanic we can infer that there is at least one x_9 for which if x_9 were a mechanic, then x_9 is playing squash. From the fact that for all x_9, if x_9 were a writer, then x_9 is a mechanic, and that for all x_9, x_9 is a writer we can infer that for all x_9, x_9 is a mechanic. Finally, from the fact that there is at least one x_9 for which if x_9 were a mechanic, then x_9 is playing squash, and that for all x_9, x_9 is a mechanic we can infer that there is at least one x_9 for which x_9 will play squash, which contradicts that For all x_9, x_9 will not play squash. Therefore, the answer is no.