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 rich, then x_4 is not sad. For all x_4, x_4 is not a mechanic. There is at least one x_4 for which x_4 is a mechanic or x_4 is sad.
There is at least one x_4 for which x_4 is sad.