Two people, A and B, start from A and B at the same time, walk towards each other, and move back and forth between A and B. A travels 120 meters per minute, and B travels 80 meters per minute. If two people meet for the first time The distance between point C and the second meeting point D is 100 meters, find the distance between A and B.
甲、乙两人分别从A、B两地同时出发，相向而行，并在A、B两地往返运动，甲每分钟行120米，乙每分钟行80米，若两人第一次相遇点C与第二次相遇点D之间的距离是100米，求A、B两地间的距离．
<gadget id="calculator">120 + 80</gadget>
<output>200</output>

<gadget id="calculator">120 - 80</gadget>
<output>40</output>

<gadget id="calculator">100 / 40</gadget>
<output>5/2 = around 2.5</output>

<gadget id="calculator">3 - 1</gadget>
<output>2</output>

<gadget id="calculator">(5/2) / 2</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">200 * (5/4)</gadget>
<output>250</output>

<result>250</result>