Two people, A and B, are walking towards each other from two places A and B at the same time. The place where they meet for the first time is 700 meters away from place A. After they respectively arrive at B and A, they return immediately, and the second meeting is 400 meters away from place B. Meet face to face. What is the distance between A and B?
甲、乙两人分别从A、B两地同时相向而行，他们第一次相遇处距A地700米，两人各自到达B、A后又立即返回，在距B地400米处第二次迎面相遇．A、B两地相距多少米．
<gadget id="calculator">700 * 3</gadget>
<output>2_100</output>

<gadget id="calculator">2_100 - 400</gadget>
<output>1_700</output>

<result>1_700</result>