Consider the following premises. There is at least one x_7 for which x_7 will play tennis or x_7 is not a taxi driver. For all x_7, x_7 is a taxi driver if and only if x_7 will play tennis. Can we infer the following from them? If we can, name the inference rule being used: For all x_7, if is not true that x_7 will play tennis if and only if x_7 is a taxi driver.
That contradicts the premises. Therefore the answer is no.