有一道英数题,
twoplacesxandyare100kilometersapart.threepeoplea,bandcleavexatthesametimefory.AdriveswithCat25kilometersperhour.Bwalksat5kilometersperhour.afteraperiodoftime.CgetsoffA'scarandwalksat5kilometersperhourwhileAdrivesbacktogetBandthentheytraveltogetherinthecattogotoy.finally,thethreepeoplegettoyatthesametime.HowlongdoesittakethemtogettoYfromX