Consider the following premises. For all y, y will take a plane if and only if y is a bartender. For all y, y is a bartender or y will make tea. For all y, y will take a plane or y will not make tea. Can we infer the following from them? If we can, name the inference rule being used: For all y, y will take a plane.
 From the fact that for all y, y will take a plane if and only if y is a bartender we can infer that for all y, if y were a bartender, then y is taking a plane via universal biconditional elimination. From the fact that for all y, y will take a plane or y will not make tea we can infer that for all y, if y makes tea, then y is taking a plane via universal rewriting. Finally, from the fact that for all y, if y were a bartender, then y is taking a plane, that for all y, if y makes tea, then y is taking a plane, and that for all y, y is a bartender or y will make tea we can infer that for all y, y will take a plane via universal disjunction elimination. Therefore, the answer is yes.