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_18, x_18 will take a plane. For all x_18, x_18 will take a plane if and only if x_18 is bored. For all x_18, if x_18 makes tea, then x_18 is bored.
For all x_18, if x_18 takes a plane, then x_18 is bored can be inferred via the universal biconditional elimination rule. For all x_18, if x_18 were bored, then x_18 is taking a plane can be inferred via the universal biconditional elimination rule.