person rides a bicycle across a bridge at a speed of 12 kilometers per hour when going up the bridge and at a speed of 24 kilometers per hour when going down the bridge. Moreover, the distance traveled by the upper bridge and the lower bridge is equal, and there is no pause in the middle. What is the average speed of this person cycling across this bridge in kilometers per hour?
某人骑自行车过一座桥，上桥速度为每小时12千米，下桥速度为每小时24千米．而且上桥与下桥所经过的路程相等，中间也没有停顿．问这个人骑车过这座桥的平均速度是每小时多少千米？
<gadget id="calculator">24 / 12</gadget>
<output>2</output>

<gadget id="calculator">24 / 24</gadget>
<output>1</output>

<gadget id="calculator">2 + 1</gadget>
<output>3</output>

<gadget id="calculator">24 / 12 / 3</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">24 * (2/3)</gadget>
<output>16</output>

<result>16</result>