What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_9, x_9 is a janitor or x_9 will play tennis. For all x_9, x_9 will listen to a song. For all x_9, if x_9 plays tennis, then x_9 is writing a letter. For all x_9, if x_9 were a janitor, then x_9 is writing a letter.
For all x_9, x_9 will write a letter.