Consider the following premises. For all x_11, x_11 is a musician or x_11 will drink water. For all x_11, x_11 will drive a car if and only if x_11 is a bartender. For all x_11, x_11 will not drive a car. There is at least one x_11 for which x_11 is a musician if and only if x_11 is a bartender. Can we infer the following from them? If we can, name the inference rule being used: There is at least one x_11 for which x_11 will drink water.
 From the fact that for all x_11, x_11 will drive a car if and only if x_11 is a bartender, and that for all x_11, x_11 will not drive a car we can infer that for all x_11, x_11 is not a bartender via universal biconditional elimination. From the fact that there is at least one x_11 for which x_11 is a musician if and only if x_11 is a bartender, and that for all x_11, x_11 is not a bartender we can infer that there is at least one x_11 for which x_11 is not a musician via existential biconditional elimination. Finally, from the fact that for all x_11, x_11 is a musician or x_11 will drink water, and that there is at least one x_11 for which x_11 is not a musician we can infer that there is at least one x_11 for which x_11 will drink water via existential disjunctive syllogism. Therefore, the answer is yes.