Consider the following premises. For all x_9, x_9 is rich. If Michael plays squash, then David is an office clerk. For all x_8, if x_8 were rich, then x_8 is an office clerk. Can we infer the following from them? If we can, name the inference rule being used: David is an office clerk.
 From the fact that for all x_9, x_9 is rich we can infer that David is rich via universal instantiation. From the fact that for all x_8, if x_8 were rich, then x_8 is an office clerk we can infer that if David were rich, then David is an office clerk via universal instantiation. From the fact that David is rich we can infer that David is rich or Michael is playing squash via addition. Finally, from the fact that if David were rich, then David is an office clerk, that if Michael plays squash, then David is an office clerk, and that David is rich or Michael is playing squash we can infer that David is an office clerk via disjunction elimination. Therefore, the answer is yes.