Problem: Mexico City:

Between 2000 and 2004 an average of 478 crimes were reported each day in Mexico City; however, the actual crime rate is thought to be much higher "since most people are reluctant to report crime". Under policies enacted by Mayor Marcelo Ebrard between 2009 and 2011, Mexico City underwent a major security upgrade with violent and petty crime rates both falling significantly despite the rise in violent crime in other parts of the country. Some of the policies enacted included the installation of 11,000 security cameras around the city and a very large expansion of the police force. Mexico City has one of the world's highest police officer-to-resident ratios, with one uniformed officer per 100 citizens.

What is one way the city tried to combat crime?
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A: installation of 11,000 security cameras

Problem: A cappella music was originally used in religious music, especially church music as well as anasheed and zemirot. Gregorian chant is an example of a cappella singing, as is the majority of secular vocal music from the Renaissance. The madrigal, up until its development in the early Baroque into an instrumentally-accompanied form, is also usually in a cappella form. Jewish and Christian music were originally a cappella,[citation needed] and this practice has continued in both of these religions as well as in Islam.
In what era was most of the vocal music considered A cappella?
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Answer: Renaissance

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Paris is a city of books and bookstores. In the 1970s, 80 percent of French-language publishing houses were found in Paris, almost all on the Left Bank in the 5th, 6th and 7th arrondissements. Since that time, because of high prices, some publishers have moved out to the less expensive areas. It is also a city of small bookstores; There are about 150 bookstores in the 5th arrondissement alone, plus another 250 book stalls along the Seine. Small Paris bookstores are protected against competition from discount booksellers by French law; books, even e-books, cannot be discounted more than five percent below their publisher's cover price.
What is the maximum amount a publishers book can be discounted?
A: five percent

Context and question: The AEA's work progressed to heavier-than-air machines, applying their knowledge of kites to gliders. Moving to Hammondsport, the group then designed and built the Red Wing, framed in bamboo and covered in red silk and powered by a small air-cooled engine. On March 12, 1908, over Keuka Lake, the biplane lifted off on the first public flight in North America.[N 24] [N 25] The innovations that were incorporated into this design included a cockpit enclosure and tail rudder (later variations on the original design would add ailerons as a means of control). One of the AEA's inventions, a practical wingtip form of the aileron, was to become a standard component on all aircraft. [N 26] The White Wing and June Bug were to follow and by the end of 1908, over 150 flights without mishap had been accomplished. However, the AEA had depleted its initial reserves and only a $15,000 grant from Mrs. Bell allowed it to continue with experiments. Lt. Selfridge had also become the first person killed in a powered heavier-than-air flight in a crash of the Wright Flyer at Fort Myer, Virginia, on September 17, 1908.
Who was the first person to die in a plane crash?
Answer: Selfridge

Question: Guinea-Bissau has several secondary schools (general as well as technical) and a number of universities, to which an institutionally autonomous Faculty of Law as well as a Faculty of Medicine have been added.
Is there an answer to this question: What institutions have added a Faculty of Medicine?

Answer: universities

Q: What is a question about this article? If the question is unanswerable, say "unanswerable".
Some of the theorists who advocate this "revisionist" critique imply that, because the "pure hunter-gatherer" disappeared not long after colonial (or even agricultural) contact began, nothing meaningful can be learned about prehistoric hunter-gatherers from studies of modern ones (Kelly, 24-29; see Wilmsen)
The "pure hunter-gatherer" appeared not long after what?
A:
unanswerable