Taotao’s family went to climb a mountain on weekends. The speed of going up the mountain is 4 kilometers per hour, and the speed of going down the mountain along the original road is 6 kilometers per hour. What is the average speed of Taotao going up and down the mountain this time in kilometers per hour?
周末涛涛一家去爬山，上山速度为4千米/小时，沿原路下山的速度为6千米/小时，那么涛涛本次上下山的平均速度为多少千米/小时．
<gadget id="calculator">1 + 1</gadget>
<output>2</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/4) + (1/6)</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">2 / (5/12)</gadget>
<output>24/5 = around 4.8</output>

<result>24/5 = around 4.8</result>