A person goes hiking on a weekend, travels 40 kilometers per hour when going up the mountain, and travels 60 kilometers per hour when returning the same way. What is the average speed of this person in kilometers per hour?
某人周末去爬山，上山时每小时行40千米，原路返回时每小时行60千米．此人往返的平均速度是每小时多少千米．
<gadget id="calculator">1 / 40</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">1 / 60</gadget>
<output>1/60 = around 0.016667</output>

<gadget id="calculator">(1/40) + (1/60)</gadget>
<output>1/24 = around 0.041667</output>

<gadget id="calculator">2 / (1/24)</gadget>
<output>48</output>

<gadget id="calculator">1 * 48</gadget>
<output>48</output>

<result>48</result>