Consider the following premises. For all z_4, if z_4 plays squash, then z_4 is a writer. For all z_4, if z_4 were fast, then z_4 is playing squash. Can we infer the following from them? If we can, name the inference rule being used: There is at least one z_4 for which the fact that z_4 were fast does not imply that z_4 is a writer.
That contradicts the premises. Therefore the answer is no.