Wang Qiang and Li Jun started running from the starting line at the same time on a 300-meter circular runway. Wang Qiang ran 6 meters per second, and Li Jun ran 4 meters per second. How many seconds later did Wang Qiang catch up with Li Jun for the first time?
王强和李军在一个300米的环形跑道上同时从起跑线上起跑，王强每秒跑6米，李军每秒跑4米．问几秒后王强第一次追上李军？
<gadget id="calculator">6 - 4</gadget>
<output>2</output>

<gadget id="calculator">300 / 2</gadget>
<output>150</output>

<result>150</result>