Consider the following premises. For all x_5, if x_5 were a politician, then x_5 is sad. There is at least one x_5 for which x_5 will drive a car or x_5 is a police officer. For all x_5, x_5 is sad if and only if x_5 is a police officer. For all x_5, if x_5 drives a car, then x_5 is a politician. Can we infer the following from them? There is at least one x_5 for which x_5 is sad.
 From the fact that for all x_5, if x_5 drives a car, then x_5 is a politician, and that for all x_5, if x_5 were a politician, then x_5 is sad we can infer that for all x_5, if x_5 drives a car, then x_5 is sad. From the fact that for all x_5, x_5 is sad if and only if x_5 is a police officer we can infer that for all x_5, if x_5 were a police officer, then x_5 is sad. Finally, from the fact that for all x_5, if x_5 drives a car, then x_5 is sad, that for all x_5, if x_5 were a police officer, then x_5 is sad, and that there is at least one x_5 for which x_5 will drive a car or x_5 is a police officer we can infer that there is at least one x_5 for which x_5 is sad. Therefore, the answer is yes.