A tree grows 1 3/4 feet per year. How long will it take the tree to grow from a height of 21 1/4 feet to a height of 37 feet?

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.