Consider the following premises. For all x_7, x_7 will make tea if and only if x_7 will work. For all x_7, x_7 is a taxi driver if and only if x_7 will make tea. For all x_7, x_7 will not work. Can we infer the following from them? For all x_7, x_7 is not a taxi driver.
 From the fact that for all x_7, x_7 is a taxi driver if and only if x_7 will make tea we can infer that for all x_7, if x_7 were a taxi driver, then x_7 is making tea. From the fact that for all x_7, x_7 will make tea if and only if x_7 will work, and that for all x_7, x_7 will not work we can infer that for all x_7, x_7 will not make tea. Finally, from the fact that for all x_7, if x_7 were a taxi driver, then x_7 is making tea, and that for all x_7, x_7 will not make tea we can infer that for all x_7, x_7 is not a taxi driver. Therefore, the answer is yes.