Its the first fucking letter faggot. P. Any number directly in front of the () belongs to it.
You're multiplying. 2(9+3) = 2 * (9+3) = 2 * 12. You call it simplifying but it's multiplication. You can't touch the 2 until you do (9+3) first. Once you do that then multiply the 2. You don't do it during the "P" part because it's the "M" part.