If a car travels from A to B, if it travels 40 kilometers per hour and arrives in 12 hours, if it travels 60 kilometers per hour, how many hours earlier can it arrive? (Solve with ratio)
一辆汽车从甲地到乙地，如果每小时行40千米，12小时到达，如果每小时行60千米，可以提前多少小时到达？(用比例解)
<gadget id="calculator">60 * 12</gadget>
<output>720</output>

<gadget id="calculator">40 * 12</gadget>
<output>480</output>

<gadget id="calculator">720 - 480</gadget>
<output>240</output>

<gadget id="calculator">240 / 60</gadget>
<output>4</output>

<result>4</result>