A and B are in places A and B respectively. It takes 20 minutes for A to travel from A to B, and 30 minutes for B to travel from B to A. If they start at the same time and walk towards each other, how long will it take for them to meet?
甲、乙两人分别在A地和B地，甲从A地到B地需要20分钟，乙从B地到A地需要30分钟，如果两个人同时出发相向而行，多长时间可以相遇？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/20) + (1/30)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">1 / (1/12)</gadget>
<output>12</output>

<result>12</result>