An express train and a slow train depart from A and B oppositely at the same time, and meet each other after 12 hours. After the encounter, the express train travels for another 8 hours to reach point B, and how many hours does the slow train have to travel to reach point A.
一辆快车和一辆慢车同时从A、B两地相对开出，经过12小时相遇．相遇后，快车又行了8小时到达B地，慢车还要行多少小时才能到达A地．
<gadget id="calculator">8 / 12</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">12 / (2/3)</gadget>
<output>18</output>

<result>18</result>