The speed of the two boats is the same in still water. They depart from the two piers of the river at the same time and meet each other after 3 hours. Given that the speed of the water flow is 4 km/h, what is the difference in kilometers between the distance traveled by the two ships A and B when they meet?
两船在静水中速度相同，它们同时自河的两个码头相对开出，3小时后相遇．已知水流速度是4千米/小时，则相遇时，甲、乙两船航行的距离相差多少千米．
<gadget id="calculator">4 * 2 * 3</gadget>
<output>24</output>

<result>24</result>