What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? Name the inference rule being used: For all x_12, x_12 is not sad or x_12 is a bartender. For all x_12, x_12 will not play tennis or x_12 is a doctor. There is at least one x_12 for which if x_12 were a bartender, then x_12 is not rich. For all x_12, x_12 is sad or x_12 will play tennis. For all x_12, x_12 is rich.
There is at least one x_12 for which x_12 is not a bartender can be inferred via the existential modus tollens rule. For all x_12, x_12 will play tennis or x_12 is a bartender can be inferred via the universal resolution rule.