In a mountaineering activity, Li Jing walked an average of 50 meters per minute when going up the mountain, reached the top of the mountain in 18 minutes, and then went down the mountain by the same route, walking an average of 75 meters per minute. How many meters per minute did Li Jing walk up and down the mountain on average?
在一次登山活动中，李晶上山时平均每分钟走50m，18分钟到达山顶，然后按原路下山，平均每分钟走75m，李晶上、下山的平均每分钟走多少米？
<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">12 + 18</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>