What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all z, if z plays squash, then z is writing a letter. For all z, z will play squash or z will not write a letter. For all z, z will not write a letter.
For all z, z will not play squash. For all z, if z writes a letter, then z is playing squash.