Mingming went to the swimming pool to swim. He swam 2 back and forth in the swimming lane, and swam a total of 200 meters. How long is the swimming lane in this swimming pool?
明明去游泳池游泳，他在泳道内游了2个来回，共游了200米，这个游泳池的泳道有多长呢？
<gadget id="calculator">2 * 2</gadget>
<output>4</output>

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

<result>50</result>