Consider the following premises. For all x_15, x_15 is a nurse or x_15 is an office clerk. For all x_15, x_15 is not a janitor. For all x_15, x_15 will play tennis if and only if x_15 is a nurse. There is at least one x_15 for which x_15 will play tennis if and only if x_15 is a janitor. Can we infer the following from them? There is at least one x_15 for which x_15 is an office clerk.
 From the fact that there is at least one x_15 for which x_15 will play tennis if and only if x_15 is a janitor, and that for all x_15, x_15 is not a janitor we can infer that there is at least one x_15 for which x_15 will not play tennis. From the fact that for all x_15, x_15 will play tennis if and only if x_15 is a nurse, and that there is at least one x_15 for which x_15 will not play tennis we can infer that there is at least one x_15 for which x_15 is not a nurse. Finally, from the fact that for all x_15, x_15 is a nurse or x_15 is an office clerk, and that there is at least one x_15 for which x_15 is not a nurse we can infer that there is at least one x_15 for which x_15 is an office clerk. Therefore, the answer is yes.