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 not make tea. For all x_1, if x_1 were poor, then x_1 is making tea. For all x_1, x_1 is a taxi driver if and only if x_1 is poor.
For all x_1, x_1 is not poor can be inferred via the universal modus tollens rule. For all x_1, if x_1 were a taxi driver, then x_1 is poor can be inferred via the universal biconditional elimination rule. For all x_1, if x_1 were poor, then x_1 is a taxi driver can be inferred via the universal biconditional elimination rule.