A 50-kg disk is fired along the positive x axis with a speed of 9 m/s toward a 57-kg disk that is initially at rest. After the collision, the 50-kg disk is found to deflect at an angle of 30? above the positive x axis and the 57-kg disk is found to deflect at an angle of 50? below the positive x axis. Determine the speed of the 50-kg disk after the collision.