Answer:
The tree is 3.15 meters tall
Step-by-step explanation:
If the shadow of a tree is 7 m long and the shadow of a person who is 0.9 m tall is 2 m long.
The ratio of height of a person to the shadow is 0.9 / 2
Let x be the height of the tree
We need to make a proportion
height of a person/ shadow = height of the tree / shadow

Cross multiply the numbers
7 * 0.9 = 2x
6.3 = 2x
Divide by 2 on both sides
x= 3.15
The tree is 3.15 meters tall