Consider the following premises. For all y, y will work or y will not make tea. There is at least one y for which if y works, then y is making tea. Can we infer the following from them? There is at least one y for which if y makes tea, then y is working.
 From the fact that for all y, y will work or y will not make tea we can infer that for all y, if y makes tea, then y is working. From the fact that for all y, if y makes tea, then y is working, and that there is at least one y for which if y works, then y is making tea we can infer that there is at least one y for which y will make tea if and only if y will work. Finally, from the fact that there is at least one y for which y will make tea if and only if y will work we can infer that there is at least one y for which if y makes tea, then y is working. Therefore, the answer is yes.