[25 points] Imagine two billiard balls on a pool table. Ball A has a mass of 7 kilograms and ball B has a mass of 2 kilograms. The initial velocity of the ball A is 6 meters per second to the right, and the initial velocity of the balloon B is 12 meters per second to the left.
When the two balls hit each other, what will happen if it is a perfectly inelastic collision?