From village A to our village, it took about an hour to go there, and it took an extra 4 kilometers per hour to return along the original road, but it only took 6 hours. A. How many kilometers are there between my two villages?
从A村到我村，去时用了右小时，沿原路返回每小时多行四千米，结果只用了6小时．A、我两村相距多n千米？
<result>21</result>