How old was Andrew Jackson when he joined the army?

13

Explanation:

Andrew Jackson, the seventh president of the United States (1829-1837), was the first to come from poverty. The youngest of three sons of Scotch-Irish immigrants, he grew up in rural South Carolina and attended local schools before leaving school to join the Army at age 13 during the American Revolution.

d. the polar jet stream   lies between the polar easterlies and trade winds should be your answer

fertile good for trade etc