There are two boats A and B sailing in the same headwater with different speeds. The distance between the two boats is 200 meters at first. At this time, a piece of wood fell from the top of boat A. When the wood board meets boat B downstream, the distance between A and B is 160 meters. When boat B catches up with boat A, how far is the board from the boat?
有A、B两艘船同在逆水中航行，速度不同，开始两船相距200米．此时A船上面掉了一块木板，木板顺流而下遇到B船时，A、B两船相距160米，问B船追上A船时，木板距离船有多远？
<result>800</result>