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 David makes tea, then Susan is playing a game. David is making tea if and only if it is sunny. Susan is not playing a game.
David is not making tea can be inferred via the modus tollens rule. If David makes tea, then it is sunny can be inferred via the biconditional elimination rule. If it is sunny, then David is making tea can be inferred via the biconditional elimination rule.