Wang Qiang swam 4 back and forth in the lanes of a swimming pool, a total of 400 meters. How long is the lane of this swimming pool?
王强在一个游泳池的泳道里游了4个来回，一共游了400米．这个游泳池的泳道长多少米．
<gadget id="calculator">400 / 4 / 2</gadget>
<output>50</output>

<result>50</result>