A and B start from A at the same time, and walk back and forth between A and B at a constant speed. The speed of A is greater than that of B. Every time A reaches A, B or encounters B, he will turn around and go back. In addition, the direction of the two people walking between AB will not change. It is known that the place where the two meet for the second time is 1200 meters away from point B, and the point where the two meet for the third time is 800 meters away from point B. How far is the location from B?
甲、乙两人同时从A地出发，在A，B两地之间匀速往返行走，甲的速度大于乙的速度，甲每次到达A地、B地或遇到乙都会调头往回走，除此以外，两人在AB之间行走方向不会改变，已知两人第二次相遇的地点距离B地1200米，第三次的相遇点距离B地800米，那么第一次相遇的地点距离B地多少米．
<gadget id="calculator">800 / 1_200</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1_200 / (2/3)</gadget>
<output>1_800</output>

<result>1_800</result>