Since the Church was restored in 1830, who has served the longest in the First Presidency.
(Answer on page 12)
Here's answer to week's question
President Joseph F. Smith served longer in the First Presidency than any other person since the Church was restored in 1830. President Smith served as a counselor to the First Presidency from 1866 (when he was 27 years old) to 1877, during the presidency of Brigham Young. President Smith served as second counselor to President John Taylor from 1880 to 1887; as second counselor to President Wilford Woodruff from 1889 to 1898; as second counselor to President Lorenzo Snow from 1898 to 1901. President Smith then served as president of the Church from 1901 to 1918, making a total of 47 years he served in the First Presidency.
Source: 1995-1996 Deseret News Church Almanac, pp. 42-43.