Detailed Instructions: In this task, you're given a statement, 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: Context: made his debut in March 1975 Link Information: Construction started on 28 November 1935 and the airport opened partly in June 1937 Question: How long had Manchester Airport been in operation for the year Keegan made his debut?
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: 38