You must first calculate how much the tree needs to grow.
Then you divide that amount by how much the tree grows per year.
37 - 21 1/4 = 36 4/4 - 21 1/4 = 15 3/4
The tree has to grow 15 3/4 ft.
Now you divide 15 3/4 by 1 3/4.
(15 3/4)/(1 3/4) = (63/4) / ( 7/4) = 63/4 * 4/7 = (63 * 4)/(4 * 7) = 63/7 = 9
It will take 9 years.
