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: William is a cashier if and only if Thomas is making tea. For all z, z will play squash. William is a cashier.
If William were a cashier, then Thomas is making tea can be inferred via the biconditional elimination rule. If Thomas makes tea, then William is a cashier can be inferred via the biconditional elimination rule.