Two people, A and B, start from point A and walk along a 400-meter circular runway at the same time. A walks 80 meters per minute, and B walks 50 meters per minute. How many minutes will it take for the two people to meet at point A again?
甲、乙两人同时从A点背向出发沿400米环行跑道行走，甲每分钟走80米，乙每分钟走50米，这二人最少用多少分钟再在A点相遇．
<result>40</result>