Consider the following premises. For all x_8, if x_8 were an astronaut, then x_8 is taking a plane. There is at least one x_8 for which if x_8 were an office clerk, then x_8 is a janitor. For all x_8, if x_8 takes a plane, then x_8 is an office clerk. For all x_8, if x_8 were a janitor, then x_8 is an astronaut. Can we infer the following from them? If we can, name the inference rule being used: There is at least one x_8 for which if x_8 takes a plane, then x_8 is a janitor.
 From the fact that for all x_8, if x_8 were a janitor, then x_8 is an astronaut, and that for all x_8, if x_8 were an astronaut, then x_8 is taking a plane we can infer that for all x_8, if x_8 were a janitor, then x_8 is taking a plane via universal transitivity. Finally, from the fact that for all x_8, if x_8 takes a plane, then x_8 is an office clerk, and that there is at least one x_8 for which if x_8 were an office clerk, then x_8 is a janitor we can infer that there is at least one x_8 for which if x_8 takes a plane, then x_8 is a janitor via existential transitivity. Therefore, the answer is yes.