A and B start from A and B at the same time and walk towards each other. If A walks 60 meters per minute and B walks 40 meters per minute, they meet at a distance of 400 meters from the midpoint. Ask: A, B The distance between the two places.
甲、乙两人分别从A、B两地同时出发，相向而行，如果甲每分钟走60米，乙每分钟走40米，在距离中点400米处两人相遇，求：A、B两地间的距离．
<gadget id="calculator">60 - 40</gadget>
<output>20</output>

<gadget id="calculator">2 / 20</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">400 * (1/10)</gadget>
<output>40</output>

<gadget id="calculator">60 + 40</gadget>
<output>100</output>

<gadget id="calculator">100 * 400 * (1/10)</gadget>
<output>4_000</output>

<result>4_000</result>