In this task, you're given a passage, further information available on a particular linked term from the statement, and a question. Your job is to generate the answer to the question by using the information provided. If there is no clear answer obtainable, output 'none'.

Q: Passage: The Yardbirds are an English blues rock band from London. Formed in May 1963, the group originally included lead vocalist Keith Relf, lead guitarist Anthony "Top" Topham, rhythm guitarist Chris Dreja, bassist Paul Samwell-Smith and drummer Jim McCarty. In October, Topham was replaced by Eric Clapton. He remained until 13 March 1965, when he left due to creative disagreements. Clapton recommended Jimmy Page to replace him, but he declined and Jeff Beck took over. Page later joined on bass the following June, after Samwell-Smith abruptly quit; Dreja later took over the role, allowing Page to join Beck on guitar. This lineup was short-lived, however, as Beck left in November 1966. The group continued as a four-piece until July 1968, when Relf and McCarty left due to creative differences, primarily with Page. Dreja initially remained, but by August Page formed a new group with vocalist Robert Plant, bassist John Paul Jones and drummer John Bonham, who later renamed themselves Led Zeppelin.
 Link Information: who later renamed themselves Led Zeppelin. Question: In what year did the Yardbirds rename themselves Led Zeppelin?

A: Answer: 1968
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Q: Passage: De Koning attended a Gymnasium in Meppel from April 1939 until September 1943. On 10 May 1940 Nazi Germany invaded the Netherlands and the government fled to London to escape the German occupation. During the German occupation De Koning continued his study but in September 1943 he joined the Dutch resistance against the German occupiers barely 17-years old. Following the end of World War II De Koning volunteered and enlisted in the Royal Netherlands East Indies Army as a Corporal serving in the Dutch East Indies from August 1945 until June 1948. De Koning applied at the Utrecht University in June 1948 majoring in Social geography and obtaining an Bachelor of Social Science degree in July 1950 and worked as a student researcher before graduating with an Master of Social Science degree in July 1958. De Koning worked as a trade association executive for the (CBTB) from February 1955 until November 1961 and worked as a researcher at the Royal Academy of Arts and Sciences from November 1961 until January 1964. De Koning worked again as a trade association executive for the Christian Farmers and Gardeners association serving as General-Secretary of the Executive Board from January 1964 until May 1971.
 Link Information: Meppel () is a municipality and a city in the northeast of the Netherlands Question: In what country did De Koning attend a gymnasium?

A: Answer: Netherlands
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Q: Passage: Roth hired 19-year-old guitar virtuoso Jason Becker to replace Vai prior to recording his third solo LP, A Little Ain't Enough. A straight-ahead hard rock album produced by Bob Rock (who had just produced Metallica's self-titled album), A Little Ain't Enough achieved RIAA gold status shortly after its January 1991 release. Before starting a support tour for A Little Ain't Enough, Becker was diagnosed with Lou Gehrig's disease, rendering him unable to perform onstage. Guitarist Joe Holmes stood in for Becker during the tour. Later in 1991, Nirvana and grunge rock emerged, altering musical tastes and suddenly making Roth's brand of hard rock seem unfashionable. Roth's band fractured shortly following the tour's completion. With one exception – 1997's well-received DLR Band album, featuring guitarist John 5 and drummer Ray Luzier – until his reconciliation with Van Halen in 2006, Roth would utilize hired-hands and studio musicians on his club and amphitheater solo tours.
 Link Information: Joe Holmes (born June 11, 1963) Question: How old is the guitarist who stood in for Becker during the tour?

A:

Show your work and conclude with the exact phrasing "Therefore, the final answer is [answer]." where [answer] is just the final number or expression that solves the problem.
user
Answer: 28
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