A ball of mass 5.0kg moving with a velocity of 10.0m/s collides with a 2.5kg ball moving in the opposite direction with a velocity of 8.0 m/s. After the collision, the balls ease and move in the same direction. Calculate the velocity of the composite body.

• A.4.0 m/s
• B.6.5 m/s
• C.8.0 m/s
• D.9.0m/s