Consider the following premises. If James goes running, then James is writing a letter. For all x_13, x_13 is a taxi driver if and only if x_13 will write a letter. For all x_13, if x_13 were a taxi driver, then x_13 is running. Can we infer the following from them? If we can, name the inference rule being used: If is not true that James is writing a letter if and only if James is running.
That contradicts the premises. Therefore the answer is no.