Problem: Due to the Budget sequestration in 2013, the USAF was forced to ground many of its squadrons. The Commander of Air Combat Command, General Mike Hostage indicated that the USAF must reduce its F-15 and F-16 fleets and eliminate platforms like the A-10 in order to focus on a fifth-generation jet fighter future. In response to squadron groundings and flight time reductions, many Air Force pilots have opted to resign from active duty and enter the Air Force Reserve and Air National Guard while pursuing careers in the commercial airlines where they can find flight hours on more modern aircraft.
Why have many US Air Force pilots opted to resign from active service? 
The answer is the following: squadron groundings and flight time reductions

Problem: Matrix groups consist of matrices together with matrix multiplication. The general linear group GL(n, R) consists of all invertible n-by-n matrices with real entries. Its subgroups are referred to as matrix groups or linear groups. The dihedral group example mentioned above can be viewed as a (very small) matrix group. Another important matrix group is the special orthogonal group SO(n). It describes all possible rotations in n dimensions. Via Euler angles, rotation matrices are used in computer graphics.
Rotation matrix groups are utilized in computer graphics with what concept?
The answer is the following: Euler angles

Problem: San Diego was ranked as the 20th-safest city in America in 2013 by Business Insider. According to Forbes magazine, San Diego was the ninth-safest city in the top 10 list of safest cities in the U.S. in 2010. Like most major cities, San Diego had a declining crime rate from 1990 to 2000. Crime in San Diego increased in the early 2000s. In 2004, San Diego had the sixth lowest crime rate of any U.S. city with over half a million residents. From 2002 to 2006, the crime rate overall dropped 0.8%, though not evenly by category. While violent crime decreased 12.4% during this period, property crime increased 1.1%. Total property crimes per 100,000 people were lower than the national average in 2008.
What type of crime increased between 2002 and 2006?
The answer is the following: property crime

Problem: On 7 January 2015, two French Muslim extremists attacked the Paris headquarters of Charlie Hebdo and killed thirteen people, and on 9 January, a third terrorist killed four hostages during an attack at a Jewish grocery store at Porte de Vincennes. On 11 January an estimated 1.5 million people marched in Paris–along with international political leaders–to show solidarity against terrorism and in defence of freedom of speech. Ten months later, 13 November 2015, came a series of coordinated terrorist attacks in Paris and Saint-Denis claimed by the 'Islamic state' organisation ISIL ('Daesh', ISIS); 130 people were killed by gunfire and bombs, and more than 350 were injured. Seven of the attackers killed themselves and others by setting off their explosive vests. On the morning of 18 November three suspected terrorists, including alleged planner of the attacks Abdelhamid Abaaoud, were killed in a shootout with police in the Paris suburb of Saint-Denis. President Hollande declared France to be in a three-month state of emergency.
How many people marched on January 11 against terrorism?
The answer is the following:
1.5 million