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 y_4, if y_4 makes tea, then y_4 is taking a plane. If David were a lawyer, then Joseph is making tea. If Joseph takes a plane, then David is a lawyer.
If Joseph takes a plane, then Joseph is making tea can be inferred via the transitivity rule.