3) A 15-foot-tall pole casts a shadow that is 6 feet long. Nearby, a tree casts a shadow that is4 feet long. How tall is the tree?

Let's use Direct Rule of Three for finding the height of the tree:
Length Distance of the shadwo
15 6
x 4
______________
6x = 15 * 4
6x = 60
Dividing by 6 at both sides
6x/6 = 60/6
x = 10
The correct answer is A. 10 feet