A circular playground with a circumference of 300 meters, A walks 100 meters per minute, B walks 60 meters per minute, A and B walk in the same direction from the starting point at the same time, how many minutes will they meet again at the starting point?
一个周长是300米环形操场，甲每分钟走100米，乙每分钟走60米，甲乙两人同时从起点同方向走，第多少分钟时他们又在起点相遇？
<gadget id="calculator">100 - 60</gadget>
<output>40</output>

<gadget id="calculator">300 / 40</gadget>
<output>15/2 = around 7.5</output>

<result>15/2 = around 7.5</result>