(-8y^2+6y-1)+(-8y^2+8y+1)-(-3y^2+9y -9)

These are the multiples of 15 but what you are probably asking or what are the factors of 15

After the experience with great britain having a monarchy, the united states realized that everyone needed to have a voice in the government. the fact that americans had no voice was the main reason for the war. thus, they created a democracy, where the people voted for their representatives and the government ruled with the consent of the people.