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_9, x_9 is not poor. For all x_9, if x_9 reads a book, then x_9 is poor. There is at least one x_9 for which x_9 will read a book if and only if x_9 will cook. For all x_9, x_9 will cook or x_9 will listen to a song.
For all x_9, x_9 will not read a book can be inferred via the universal modus tollens rule. There is at least one x_9 for which if x_9 reads a book, then x_9 is cooking can be inferred via the existential biconditional elimination rule. There is at least one x_9 for which if x_9 cooks, then x_9 is reading a book can be inferred via the existential biconditional elimination rule.