Answer: 21 feet.
Step-by-step explanation:
1. You know that the tree casts a 28 feet shadow and that a 6 feet fence post casts a 8 feet shadow, then, you can write the following proportion to solve this problem:
[tex]\frac{x}{28}=\frac{6}{8}[/tex]
2. When you solve for the height ot tree (x), you obtain the following result:
[tex]x=\frac{28*6}{8}\\x=21[/tex]
3. Therefore, the height of the tree is 21 feet.
