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_7, x_7 will listen to a song if and only if x_7 will drink water. For all x_7, x_7 will not write a letter. For all x_7, x_7 will listen to a song if and only if x_7 will write a letter.
For all x_7, if x_7 listens to a song, then x_7 is drinking water can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 listens to a song, then x_7 is writing a letter can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 drinks water, then x_7 is listening to a song can be inferred via the universal biconditional elimination rule. For all x_7, if x_7 writes a letter, then x_7 is listening to a song can be inferred via the universal biconditional elimination rule. For all x_7, x_7 will not listen to a song can be inferred via the universal biconditional elimination rule.