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_7, x_7 is rich or x_7 is a cashier. For all x_7, if x_7 were rich, then x_7 is playing tennis. For all x_7, if x_7 were a cashier, then x_7 is playing tennis. For all x_7, x_7 is a taxi driver.
For all x_7, x_7 will play tennis can be inferred via the universal disjunction elimination rule.