Answer: The height of fir tree is 9 meters and the height of pine tree is 12 meters.
Explanation:
Given : The combined height of one fir tree and one pine tree = 21 meters.
Since, the height of 4 fir trees stacked on top of each other is 24 meters taller than one pine tree.
Let x be the height of fir tree and y be the height of pine tree.
Then we get the following equations:
![x+y=21...............(1)\\4x-y=24.........(2)](https://img.qammunity.org/2020/formulas/mathematics/high-school/rz6zaoku8g263i276l3n3c0kxcy9shi3jh.png)
Adding (1) and (2) we get
![5x=45\\\Rightarrow\ x=9](https://img.qammunity.org/2020/formulas/mathematics/high-school/rkcfhfcim8dr1ur24ndqkpoychc9qntwal.png)
Substitute the value of x in (1), we get
![9+y=21\\\Rightarrow\ y=21-9=12](https://img.qammunity.org/2020/formulas/mathematics/high-school/njcdpkddehirpd71r5ezjq3x29xm2ya6s3.png)
Hence, the height of fir tree is 9 meters and the height of pine tree is 12 meters.