and B are 1000 meters apart. A starts from A and B starts from B at the same time and walks towards each other. After meeting, they continue to move forward and return immediately after arriving at their respective destinations. A travels 60 meters per minute, and B travels 40 meters per minute. How many minutes does it take for A to catch up with B for the first time? ．
A、B相距1000米．甲从A，乙从B同时出发相向而行，相遇后继续前进，到达各自目的地后立刻返回，甲每分钟行60米，乙每分钟行40米，经过多少分钟甲第一次追上乙．
<gadget id="calculator">60 - 40</gadget>
<output>20</output>

<gadget id="calculator">1_000 / 20</gadget>
<output>50</output>

<result>50</result>