Answer:4.08 ft a year or 1 and 5/8 feet a year (approx)
Explanation:
It's 12.5 feet the first year
51 feet 5 years later
If you do the math and divide 51 by 12.5, you get 4.08 which is around 1 and 5/8 ft
12.5x4.08 is 51 feet.
So the tree grows approximately 1 and 5/8 feet a year