In a mountaineering competition, Li Ming went up the mountain and walked 50 meters per minute. He reached the top of the mountain in 18 minutes.
在一次登山比赛中，李明上山每分钟走50米，18分钟到达山顶，按原路下山时，每分钟走75米，求李明上下山往返一次的平均速度．
<gadget id="calculator">18 / 75</gadget>
<output>6/25 = around 0.24</output>

<gadget id="calculator">50 * (6/25)</gadget>
<output>12</output>

<gadget id="calculator">18 + 12</gadget>
<output>30</output>

<gadget id="calculator">2 / 30</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">50 * 18 * (1/15)</gadget>
<output>60</output>

<result>60</result>