Zhang Ning and Wang Ming walk opposite directions at the same time on the circular runway at the same time. Zhang Ning walks 45 meters per minute, and Wang Ming walks 35 meters per minute. The two meet for the first time after 5 minutes. The length of one lap of the runway is How much rice?
张宁和王明在环形跑道上从同一点同时反向而行，张宁每分钟走45米，王明每分钟走35米，5分钟后两人第一次相遇，跑道一圈的长是多少米？
<gadget id="calculator">45 + 35</gadget>
<output>80</output>

<gadget id="calculator">80 * 5</gadget>
<output>400</output>

<result>400</result>