Xiao Ming and Xiao Qing are running on the circular track. They start from the same place and walk in opposite directions. Xiaoming runs 3m per second, and Xiaoqing runs 5m per second. After 50 seconds, the two met for the first time on the runway and asked: How long is the runway in meters?
小明和小青在环形跑道上跑步，两人从同一地点出发，反向而行．小明每秒跑3m，小青每秒跑5m．经过50秒，两人在跑道上第1次相遇，问：跑道长多少米？
<gadget id="calculator">5 + 3</gadget>
<output>8</output>

<gadget id="calculator">8 * 50</gadget>
<output>400</output>

<result>400</result>