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_9, x_9 is not an electrician. For all x_9, if x_9 were a cashier, then x_9 is driving a car. There is at least one x_9 for which x_9 will play tennis if and only if x_9 is a cashier. For all x_9, if x_9 drives a car, then x_9 is poor. For all x_9, x_9 is an electrician if and only if x_9 is poor.
For all x_9, if x_9 were a cashier, then x_9 is poor can be inferred via the universal transitivity rule. For all x_9, if x_9 were an electrician, then x_9 is poor can be inferred via the universal biconditional elimination rule. There is at least one x_9 for which if x_9 plays tennis, then x_9 is a cashier can be inferred via the existential biconditional elimination rule. For all x_9, if x_9 were poor, then x_9 is an electrician can be inferred via the universal biconditional elimination rule. There is at least one x_9 for which if x_9 were a cashier, then x_9 is playing tennis can be inferred via the existential biconditional elimination rule. For all x_9, x_9 is not poor can be inferred via the universal biconditional elimination rule.