Xiaojun swam back and forth twice in the lane of the swimming pool, and swam a total of 200 meters. How long is the lane of this swimming pool?
小军在游泳池的泳道内游了两个来回，共游了200米，这个游泳池的泳道有多长？
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

<gadget id="calculator">200 / 4</gadget>
<output>50</output>

<result>50</result>