Consider the following premises. For all x_10, x_10 is a mechanic if and only if x_10 is poor. For all x_10, x_10 will not play tennis or x_10 is a doctor. For all x_10, x_10 is poor if and only if x_10 is a doctor. There is at least one x_10 for which x_10 will play tennis or x_10 is a mechanic. Can we infer the following from them? For all x_10, x_10 is not poor.
 From the fact that there is at least one x_10 for which x_10 will play tennis or x_10 is a mechanic, and that for all x_10, x_10 will not play tennis or x_10 is a doctor we can infer that there is at least one x_10 for which x_10 is a mechanic or x_10 is a doctor. From the fact that for all x_10, x_10 is a mechanic if and only if x_10 is poor we can infer that for all x_10, if x_10 were a mechanic, then x_10 is poor. From the fact that for all x_10, x_10 is poor if and only if x_10 is a doctor we can infer that for all x_10, if x_10 were a doctor, then x_10 is poor. Finally, from the fact that for all x_10, if x_10 were a mechanic, then x_10 is poor, that for all x_10, if x_10 were a doctor, then x_10 is poor, and that there is at least one x_10 for which x_10 is a mechanic or x_10 is a doctor we can infer that there is at least one x_10 for which x_10 is poor, which contradicts that For all x_10, x_10 is not poor. Therefore, the answer is no.