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_12, if x_12 drinks water, then x_12 is a mechanic. For all x_12, x_12 will listen to a song or x_12 will not read a book. There is at least one x_12 for which x_12 will drink water if and only if x_12 will listen to a song.
For all x_12, if x_12 reads a book, then x_12 is listening to a song can be inferred via the universal rewriting rule. There is at least one x_12 for which if x_12 drinks water, then x_12 is listening to a song can be inferred via the existential biconditional elimination rule. There is at least one x_12 for which if x_12 listens to a song, then x_12 is drinking water can be inferred via the existential biconditional elimination rule.