This question is off-topic, but I'm answering it assuming you meant to categorize as maths.
Answer:
[tex]-9(2P+1)[/tex] or [tex]-3^2(2P+1)[/tex]
Explanation:
Factoring
It consists of converting an algebraic expression, usually as a polynomial into two or more factored terms.
We must find the greatest possible common factor and use it to modify the original expression.
The given expression is
[tex]-18P-9[/tex]
It's evident that both terms have a numeric common factor of -9. Let's factor by -9. We must divide each term by -9 to get:
[tex]-9(2P+1)[/tex]
We can even factor further by writing
[tex]-3^2(2P+1)[/tex]
