Get like numbers together so get the p with the p and the extra numbers together and if they changes sides change their signs so if it was positive and you switched sides it would then become negative so:
5p-9=2p-12
5p-2p=-12+9
Then continue the problem and add or subtract depending on the signs.
5p-2p=-12+9
3p=-3
Then get the p only. To do that you need to divide by 3 since you are multiplying it on its starting side.
3p=-3
p=-3/3
p=-1
So you get a final answer of p=-1
