There are three people A, B, and C walking on a playground track. A walks 80 meters per minute, B walks 120 meters per minute, and C walks 70 meters per minute. It is known that the circumference of the playground runway is 400 meters. If three people start from the same place in the same direction at the same time, after a few minutes, can the three people meet for the first time?
有甲、乙、丙三个人在操场跑道上步行，甲每分钟走80米，乙每分钟走120米，丙每分钟走70米．已知操场跑道周长为400米，如果三个人同时同向从同一地点出发，问几分钟后，三个人可以首次相遇？
<gadget id="calculator">120 - 80</gadget>
<output>40</output>

<gadget id="calculator">400 / 40</gadget>
<output>10</output>

<gadget id="calculator">400 / 10</gadget>
<output>40</output>

<result>40</result>