It takes 12 hours for an express train to travel from city A to city B, with an average travel speed of 112 kilometers per hour. Another slow train travels 84 kilometers per hour. How long does it take from city A to city B?
一列快车从A市到B市要12小时，平均每小时行112千米．另一列慢车每小时行84千米．它从A市到B市要多长时间？
<gadget id="calculator">12 / 84</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">112 * (1/7)</gadget>
<output>16</output>

<result>16</result>