The path from the bottom of the mountain to the top of the mountain is 1200 meters long. Xiao Wang’s speed up the mountain is 20 m/min, and his speed down the mountain is 30 m/min. What is Xiao Wang’s average speed up and down the mountain?
从山下到山顶的小路长1200米，小王上山的速度是20米/分钟，下山的速度是30米/分钟，问小王上下山的平均速度是多少？
<gadget id="calculator">1_200 * 2</gadget>
<output>2_400</output>

<gadget id="calculator">1_200 / 20</gadget>
<output>60</output>

<gadget id="calculator">1_200 / 30</gadget>
<output>40</output>

<gadget id="calculator">60 + 40</gadget>
<output>100</output>

<gadget id="calculator">2_400 / 100</gadget>
<output>24</output>

<result>24</result>