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: If Elisabeth cooks, then Thomas is making tea. If Thomas makes tea, then Elisabeth is cooking. For all x_9, x_9 will play a game if and only if x_9 will make tea. Thomas is not playing a game.
For all x_9, if x_9 plays a game, then x_9 is making tea can be inferred via the universal biconditional elimination rule. For all x_9, if x_9 makes tea, then x_9 is playing a game can be inferred via the universal biconditional elimination rule.