I will give brainliest to whoever answers this question. Also if you can please explain how you solved it I would appreciate it!

Answer:
40.25 feet tall
Step-by-step explanation:
There is a small triangle made by the boy and the three feet of shadow. This triangle when scaled up will be the same as the flag and the full shadow.
To do this you need to find how much to multiply 3 by to get 23.
First you do 23/3 which will give you 7.6 repeating. or 7.6666666666... (same thing)
If you then multiply that number by the boy's height 5.25 you will get the answer 40.25.
This is because the triangle the flag creates is 7.666... times larger than the triangle the boy creates.