Pretty sure it’s number 1
Answer: For a fence that has 18 posts he needs 36 rails.
Step-by-step explanation:
Hi, to answer this question we have to use proportions:
Each section use 3 vertical fence post and 6 horizontal rails
The proportion is = 3 post /6 rails
For 18 posts:
18 posts / x rails.
3 /6 = 18 /x
Solving for x:
x = 18 / (3/6)
x = 36 rails
For a fence that has 18 posts he needs 36 rails.
Feel free to ask for more if needed or if you did not understand something.
We have

We start by calculating square root:

We can rewrite 4 in base of 2:

Now we can calculate this by using rule of same base and different exponent: