第37問配点 ３点
次の英文の解答として最も適切なものを，後記１から５までの中から選びなさい。（解答欄は，［№37］）
Mr. Smith, 45 years old, has a son who is 12 years old, and both father and son have the same birthday. How old was the boy when Mr. Smith was 10 times as old as his son? You may assume that all months have the same number of days.
１. 3 years 6 months
２. 3 years 7 months
３. 3 years 8 months
４. 3 years 9 months
５. 3 years 10 months