Consider the following premises. For all x_15, x_15 is not a server. For all x_15, x_15 is a sailor or x_15 will play squash. For all x_15, x_15 will drive a car if and only if x_15 is a sailor. There is at least one x_15 for which x_15 will drive a car if and only if x_15 is a server. Can we infer the following from them? If we can, name the inference rule being used: There is at least one x_15 for which x_15 will play squash.
 From the fact that there is at least one x_15 for which x_15 will drive a car if and only if x_15 is a server, and that for all x_15, x_15 is not a server we can infer that there is at least one x_15 for which x_15 will not drive a car via existential biconditional elimination. From the fact that for all x_15, x_15 will drive a car if and only if x_15 is a sailor, and that there is at least one x_15 for which x_15 will not drive a car we can infer that there is at least one x_15 for which x_15 is not a sailor via existential biconditional elimination. Finally, from the fact that for all x_15, x_15 is a sailor or x_15 will play squash, and that there is at least one x_15 for which x_15 is not a sailor we can infer that there is at least one x_15 for which x_15 will play squash via existential disjunctive syllogism. Therefore, the answer is yes.