Two passenger cars, one big and one small, depart from A and B at the same time in opposite directions. The speed ratio of the large and small buses is 4:5. The two cars meet each other 60 minutes after leaving and continue to move forward. How many minutes later does the big bus arrive at the destination than the small one?
大小两客车从甲乙两地同时相向开出，大小客车的速度比为4：5，两车开出后60分钟相遇，并继续前进，大客车比小客车晚多少分钟到达目的地．
<result>27</result>