The equation for the number of books in the school library is given by:

$y = 8x + 170$

Where:

• $y$ represents the total number of books in the library,
• $x$ represents the number of months since the principal started buying books,
• 170 is the initial number of books in the library.

In this equation, the coefficient of $x$ (which is 8) represents the rate at which books are added each month.

Therefore, the school is adding 8 books to the library every month.

Would you like more details or have any other questions?

Here are some related questions to consider:

1. How many books will the library have after 5 months?
2. What will the total number of books be after 10 months?
3. If the library needs 250 books, how many months will it take to reach that number?
4. How would the equation change if the school added 12 books per month instead of 8?
5. What does the constant 170 represent in the context of this problem?

Tip: In equations like this, the coefficient of $x$ usually represents the rate of change or how much something increases (or decreases) per unit time.