large truck drives a 240-kilometer expressway from a certain town to a county, and then a 200-kilometer ordinary road. The speed of the expressway is 80 km/h, and the speed of the ordinary road is 40 km/h. How much time is saved on the expressway compared with the ordinary road?
一辆大货车从某镇到县城开过一段高速路240千米，又开过一段200千米普通公路．高速路时速为80千米/时，普通公路时速为40千米/时，高速路比普通公路节约多少时间？
<gadget id="calculator">200 / 40</gadget>
<output>5</output>

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

<gadget id="calculator">5 - 3</gadget>
<output>2</output>

<result>2</result>