Consider the following premises. For all x_9, x_9 is a sailor. For all x_9, x_9 will make tea or x_9 will take a plane. For all x_9, if x_9 makes tea, then x_9 is playing tennis. For all x_9, if x_9 takes a plane, then x_9 is playing tennis. Can we infer the following from them? If we can, name the inference rule being used: There is at least one x_9 for which neither x_9 will play tennis nor x_9 is a cashier.
 From the fact that for all x_9, if x_9 makes tea, then x_9 is playing tennis, that for all x_9, if x_9 takes a plane, then x_9 is playing tennis, and that for all x_9, x_9 will make tea or x_9 will take a plane we can infer that for all x_9, x_9 will play tennis via universal disjunction elimination. From the fact that for all x_9, x_9 will play tennis, and that for all x_9, x_9 is a sailor we can infer that for all x_9, x_9 will play tennis and x_9 is a sailor via universal conjunction. From the fact that for all x_9, x_9 will play tennis and x_9 is a sailor we can infer that for all x_9, x_9 will play tennis via universal simplification. Finally, from the fact that for all x_9, x_9 will play tennis we can infer that for all x_9, x_9 will play tennis or x_9 is a cashier via universal addition, which contradicts that There is at least one x_9 for which neither x_9 will play tennis nor x_9 is a cashier. Therefore, the answer is no.