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 cooks, then z is writing a letter. For all z, z is not sad or z will drive a car. For all z, z will drive a car if and only if z will write a letter. For all z, z is sad or z will cook.
For all z, z will cook or z will drive a car. For all z, if z drives a car, then z is writing a letter. For all z, if z writes a letter, then z is driving a car.