The first thing that we want to do is bring like terms to either sides of the equation. That means that we want every number with a "p" on one side of the "=" sign and everything without a "p" on the other side of the "="
6 + 2p = 24
6 - 6 + 2p = 24 - 6 (bring like terms to left side)
2p = 18
(2p) / 2 = 18 / 2 (divide both sides by 2)
p = 9
So the answer is A.
Hope this helped!! :D