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_13, if x_13 were a carpenter, then x_13 is playing squash. For all x_13, if x_13 were a cashier, then x_13 is a carpenter. There is at least one x_13 for which x_13 will make tea if and only if x_13 is a cashier. For all x_13, if x_13 plays squash, then x_13 is making tea.
For all x_13, if x_13 were a carpenter, then x_13 is making tea can be inferred via the universal transitivity rule. For all x_13, if x_13 were a cashier, then x_13 is playing squash can be inferred via the universal transitivity rule. There is at least one x_13 for which if x_13 makes tea, then x_13 is a cashier can be inferred via the existential biconditional elimination rule. There is at least one x_13 for which if x_13 were a cashier, then x_13 is making tea can be inferred via the existential biconditional elimination rule.