From point A to point B, it is known that the speed ratio of cars A and B is 4:3, and it takes 9 hours for car A to travel the entire distance, how much time does it take for vehicle B to travel the entire distance?
从A地到B地，已知甲乙两车的速度比为4：3，甲车行完全程共用9时，求乙车行完全程共用多少时？
<result>12</result>