Consider the following premises. For all z_4, z_4 is a server if and only if z_4 will drink water. For all z_4, if z_4 were a taxi driver, then z_4 is a server. There is at least one z_4 for which z_4 will drink water if and only if z_4 is a taxi driver. Can we infer the following from them? If we can, name the inference rule being used: For all z_4, if is not true that z_4 will drink water if and only if z_4 is a taxi driver.
That contradicts the premises. Therefore the answer is no.