Consider the following premises. Thomas is an electrician if and only if Joseph is a janitor. For all x_15, if x_15 drives a car, then x_15 is an electrician. David is poor if and only if Thomas is driving a car. Joseph is not a janitor. Can we infer the following from them? David is not poor.
 From the fact that for all x_15, if x_15 drives a car, then x_15 is an electrician we can infer that if Thomas drives a car, then Thomas is an electrician. From the fact that Thomas is an electrician if and only if Joseph is a janitor, and that Joseph is not a janitor we can infer that Thomas is not an electrician. From the fact that if Thomas drives a car, then Thomas is an electrician, and that Thomas is not an electrician we can infer that Thomas is not driving a car. Finally, from the fact that David is poor if and only if Thomas is driving a car, and that Thomas is not driving a car we can infer that David is not poor. Therefore, the answer is yes.