Consider the following premises. There is at least one x_9 for which x_9 will take a plane if and only if x_9 will make tea. For all x_9, x_9 will cook or x_9 will make tea. For all x_9, x_9 will not cook. 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 x_9 will take a plane.
 From the fact that there is at least one x_9 for which x_9 will take a plane if and only if x_9 will make tea we can infer that there is at least one x_9 for which if x_9 makes tea, then x_9 is taking a plane via existential biconditional elimination. From the fact that for all x_9, x_9 will cook or x_9 will make tea, and that for all x_9, x_9 will not cook we can infer that for all x_9, x_9 will make tea via universal disjunctive syllogism. Finally, from the fact that there is at least one x_9 for which if x_9 makes tea, then x_9 is taking a plane, and that for all x_9, x_9 will make tea we can infer that there is at least one x_9 for which x_9 will take a plane via existential modus ponens. Therefore, the answer is yes.