In a mountaineering competition, Xiaogang walked 40 meters per minute when he went up the mountain, reached the top of the mountain in 18 minutes, and then went down the mountain on the same road, walking 60 meters per minute, what is the average speed of Xiaogang back and forth in meters per minute.
在一次登山比赛中，小刚上山时每分钟走40米，18分钟达到山顶，然后按原路下山，每分钟走60米，小刚往返的平均速度是每分多少米．
<gadget id="calculator">40 * 18 * 2</gadget>
<output>1_440</output>

<gadget id="calculator">18 / 60</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">40 * (3/10)</gadget>
<output>12</output>

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

<gadget id="calculator">1_440 / 30</gadget>
<output>48</output>

<result>48</result>