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_10, x_10 will drink water or x_10 is a cashier. For all x_10, x_10 is not a server. For all x_10, x_10 will play tennis. For all x_10, x_10 is a server if and only if x_10 will drink water.
For all x_10, if x_10 were a server, then x_10 is drinking water can be inferred via the universal biconditional elimination rule. For all x_10, if x_10 drinks water, then x_10 is a server can be inferred via the universal biconditional elimination rule. For all x_10, x_10 will not drink water can be inferred via the universal biconditional elimination rule.