In this task, you're given a passage, further information available on a particular linked term from the statement, and an answer term. Your job is to generate a question that can use the information provided to obtain the given answer. You should use the information on both passage and link information to create the question. Note that the answer to the question should be exactly the given answer, and if the answer is none, the answer to the question shouldn't be obtainable from the passage or linked information.

Let me give you an example: Passage: The group was occasionally diverted from strategic missions to carry out air support and interdiction missions. It supported Operation Overlord, the invasion of Normandy by attacking transportation targets, including bridges, along with airfields and strong points in France. On D Day, the squadron and the rest of the 446th Group led the first heavy bomber mission of the day. The 446th aided ground forces at Caen and Saint-Lo during July by hitting bridges, gun batteries, and enemy troops. During Operation Market Garden, the attempt to seize a bridgehead across the Rhine in the Netherlands, the 704th dropped supplies to allied troops near Nijmegen. It struck lines of communications during the Battle of the Bulge. During Operation Varsity in March 1945, it supplied ground and airborne troops near Wesel. The squadron flew its last combat mission on 25 April 1945 against Salzburg, Austria. The group had flown 273 missions and had lost 58 aircraft during the war,
. Link Information: Operation Market Garden was a failed World War II military operation fought in the Netherlands from 17 to 25 September 1944. Answer: from 17 to 25 September 1944
The answer to this example can be: When did the operation during which the 704th dropped supplies to allied troops near Nijmegen begin?
Here is why: The passage describes the 704th's actions during Operation Market Garden, and the answer specifies when the operation happened.

OK. solve this:
Passage: The Derg overthrew the Ethiopian Empire and Emperor Haile Selassie in a coup d'etat on 12 September 1974, establishing Ethiopia as a Marxist-Leninist communist state with itself as a military junta and provisional government. Various left-wing, ethnic, and anti-communist opposition groups supported by the United States began armed resistance to the Soviet-backed Derg, in addition to the Eritrean separatists already fighting in the Eritrean War of Independence. The Derg used military campaigns and the Qey Shibir (Ethiopian Red Terror) to repress the rebels. By the mid-1980s, various issues such as the 19831985 famine, economic decline and other after-effects of Derg policies ravaged Ethiopia, increasing popular support for the rebels. The Derg dissolved itself in 1987, establishing the People's Democratic Republic of Ethiopia (PDRE) under the Workers' Party of Ethiopia (WEP) in an attempt to maintain its rule. The Soviet Union ended its support for the PDRE in the late-1980s and the government was overwhelmed by the increasingly victorious rebel groups. In May 1991, the PDRE was defeated in Eritrea and President Mengistu Haile Mariam fled the country. The Ethiopian Civil War ended on 4 June 1991 when the Ethiopian People's Revolutionary Democratic Front (EPRDF), a coalition of left-wing ethnic rebel groups, entered the capital Addis Ababa and overthrew the WEP. The PDRE was dissolved and replaced with the Tigray People's Liberation Front-led Transitional Government of Ethiopia.
Link Information: Haile Selassie I (, ; born Lij Tafari Makonnen Woldemikael; 23 July 1892 27 August 1975) was Crown Prince and Regent of the Ethiopian Empire from 1916 to 1928, and then King and Regent from 1928 to 1930, and finally Emperor from 1930 to 1974. Answer: 58
Answer:
How many years had the Emperor Haile Selassie been in power when the Derg overthrew his rule in 1974?