★Xiao Zhang and Xiao Li are running on the circular track. They start from the same place and walk in opposite directions. Xiao Zhang's speed is 4 m/s, Xiao Li's speed is 6 m/s, and the two meet for the second time after 80 seconds. How long is the circular runway in meters?
★小张和小李在环形跑道上跑步，两人从同一地点出发，反向而行．小张的速度是4米/秒，小李的速度是6米/秒，经过80秒两人第二次相遇．环形跑道长多少米？
<gadget id="calculator">4 + 6</gadget>
<output>10</output>

<gadget id="calculator">80 / 2</gadget>
<output>40</output>

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

<result>400</result>