car travels from A to B at 54 kilometers per hour, arrives at B in 12 hours, and travels 72 kilometers per hour when returning. How many hours does it take to return?
一辆汽车从甲地到乙地，每小时行54千米，12小时到达乙地，返回时每小时行72千米，返回时用了几个小时？
<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>