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_1, x_1 will play tennis if and only if x_1 is a cashier. For all x_1, if x_1 were a cashier, then x_1 is playing tennis.
For all x_1, if x_1 plays tennis, then x_1 is a cashier can be inferred via the universal biconditional elimination rule. For all x_1, if x_1 were a cashier, then x_1 is playing tennis can be inferred via the universal biconditional elimination rule.