boat goes back and forth between A and B. It is known that the speed of the boat in still water is 9 kilometers per hour. The time ratio of the time spent going backwards and forwards is 2:1. Because of the heavy rain one day, the speed of the water flow is the original 2 times, the boat took 10 hours to go back and forth, how many kilometers is the distance between A and B?
一条船往返于甲、乙两地之间，已知船在静水中速度为每小时9千米，平时逆行与顺行所用的时间比为2：1，一天因为下暴雨，水流速度为原来的2倍，这条船往返共用了10小时，问甲、乙两地相距多少千米？
<result>25</result>