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_10, x_10 is excited or x_10 is an office clerk. For all x_10, x_10 is an office clerk if and only if x_10 will work. For all x_10, x_10 is happy. For all x_10, if x_10 were excited, then x_10 is working.
For all x_10, if x_10 were an office clerk, then x_10 is working can be inferred via the universal biconditional elimination rule. For all x_10, if x_10 works, then x_10 is an office clerk can be inferred via the universal biconditional elimination rule.