Consider the following premises. There is at least one x_7 for which x_7 is an electrician or x_7 is not an astronaut. For all x_7, x_7 is an electrician if and only if x_7 will take a plane. For all x_7, x_7 will take a plane or x_7 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_7 for which x_7 is an electrician.
 From the fact that there is at least one x_7 for which x_7 is an electrician or x_7 is not an astronaut we can infer that there is at least one x_7 for which if x_7 were an astronaut, then x_7 is an electrician via existential rewriting. From the fact that for all x_7, x_7 is an electrician if and only if x_7 will take a plane we can infer that for all x_7, if x_7 takes a plane, then x_7 is an electrician via universal biconditional elimination. Finally, from the fact that for all x_7, if x_7 takes a plane, then x_7 is an electrician, that there is at least one x_7 for which if x_7 were an astronaut, then x_7 is an electrician, and that for all x_7, x_7 will take a plane or x_7 is an astronaut we can infer that there is at least one x_7 for which x_7 is an electrician via existential disjunction elimination. Therefore, the answer is yes.