What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_4, if x_4 were sad, then x_4 is not driving a car. For all x_4, if x_4 works, then x_4 is sad. There is at least one x_4 for which if x_4 were sad, then x_4 is working. For all x_4, x_4 will drive a car.
For all x_4, x_4 is not sad. There is at least one x_4 for which x_4 is sad if and only if x_4 will work. There is at least one x_4 for which x_4 will work if and only if x_4 is sad.