Two boys, Dudi and Gani, run back and forth between two points A and B at a constant speed without stopping. Dudi's speed is 1.5 times Gani's speed. Dudi runs from A to B while Gani from B to A. They both start at the same time. The two boys meet for the first time at 800 meters away from B. How far are the boys from A when they meet for the second time?

　　翻译：两个男孩小杜和小嘉在甲乙两地之间以恒定的速度不断来回跑。小杜的速度是小嘉速度的1.5倍。小杜从甲地开始向乙地跑，而小嘉从乙地开始向甲地跑。这两个男孩第一次相遇时距离乙地800米，问第二次相遇时距离甲地多远？

　　解答：第一次相遇时小嘉跑了800米，所以小杜跑了1200米，甲乙两地距离2000米。第二次相遇时，两人共跑的距离是甲乙两地距离的三倍6000米，所以小嘉跑了2400米，小杜跑了3600米，小嘉跑到了甲地又往乙地回跑了400米，小杜跑到了乙地又往甲地回跑了1600米，距离甲地400米。

　　点评：其实本题的数量关系非常简单，还可用折线图解答。