What can be inferred from the following premises in a single inference step (ignoring inferences that add new predicates or constants)? For all x_6, x_6 will climb a mountain if and only if x_6 is a janitor. For all x_6, if x_6 climbs a mountain, then x_6 is writing a letter. For all x_6, if x_6 writes a letter, then x_6 is a janitor.
For all x_6, if x_6 climbs a mountain, then x_6 is a janitor. For all x_6, if x_6 climbs a mountain, then x_6 is a janitor. For all x_6, if x_6 were a janitor, then x_6 is climbing a mountain.