Consider the following premises. Jessica is playing a game or Richard is playing tennis. If Jessica plays a game, then Richard is a taxi driver. For all x_9, x_9 is a taxi driver if and only if x_9 will play tennis. Can we infer the following from them? If we can, name the inference rule being used: Richard is a taxi driver.
 From the fact that for all x_9, x_9 is a taxi driver if and only if x_9 will play tennis we can infer that for all x_9, if x_9 plays tennis, then x_9 is a taxi driver via universal biconditional elimination. From the fact that for all x_9, if x_9 plays tennis, then x_9 is a taxi driver we can infer that if Richard plays tennis, then Richard is a taxi driver via universal instantiation. Finally, from the fact that if Jessica plays a game, then Richard is a taxi driver, that if Richard plays tennis, then Richard is a taxi driver, and that Jessica is playing a game or Richard is playing tennis we can infer that Richard is a taxi driver via disjunction elimination. Therefore, the answer is yes.