and B start from AB at the same time and walk towards each other. They meet at a distance of 240 meters from A. After meeting, they continue to move forward. After arriving at BA respectively, they return immediately, and the second time they are 80 meters away from A. meet, find the distance between AB and AB.
甲、乙两人同时从AB两地出发相向而行，距A地240米处相遇，相遇后又继续前行，分别到达BA两地后又立即返回，第二次又在距A地80米处相遇，求AB两地的距离．
<gadget id="calculator">240 * 3</gadget>
<output>720</output>

<gadget id="calculator">720 + 80</gadget>
<output>800</output>

<gadget id="calculator">800 / 2</gadget>
<output>400</output>

<result>400</result>