The road from city A to city B is 160 kilometers long. A car travels at a speed of 80 km/h on a highway and at 40 km/h on an ordinary road. How much time is saved by taking the expressway from city A to city B compared to ordinary roads?
A城到B城的公路长160千米．一辆汽车走高速路的速度是80千米/时，走普通公路的速度是40千米/时．从A城去B城走高速路比普通公路节省多少时间？
<gadget id="calculator">160 / 40</gadget>
<output>4</output>

<gadget id="calculator">160 / 80</gadget>
<output>2</output>

<gadget id="calculator">4 - 2</gadget>
<output>2</output>

<result>2</result>