The total length of the road from A to B is 240 km. A car travels at 80 km/h on a freeway and at 40 km/h on an ordinary road. How much time does it take to travel from A to B by expressway rather than by ordinary road?
甲地到乙地的公路全长240千米．一辆汽车走高速公路的速度是80千米/小时，走普通路的速度是40千米/小时．从甲地到乙地走高速公路比走普通公路节约多长时间？
<gadget id="calculator">240 / 40</gadget>
<output>6</output>

<gadget id="calculator">240 / 80</gadget>
<output>3</output>

<gadget id="calculator">6 - 3</gadget>
<output>3</output>

<result>3</result>