Answer:
b b.b b b b b b b b b b b b b b b b b b
Step-by-step explanation:
b b b
The number is (2√3) / 3
To find the missing number, convert what it says in words to an equation:

Divide both sides by 15:

Take the square root:
You can use linear equations if something is being raised or decreased with the same linear function. Such as temperature or the amount of books that get sold.