A truck drives from A to B at a speed of 54 km/h, and it takes 12 hours to go. The speed when returning is 72 km/h, how long did it take to return?
一辆货车从甲地开往乙地，去时速度是54千米/时，去时用了12小时．返回时速度是72千米/时，返回时用了多少时间？
<gadget id="calculator">12 / 72</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">54 * (1/6)</gadget>
<output>9</output>

<result>9</result>