The road from Wuchuan County to Zunyi is about 180 kilometers long. The average speed of a car on the highway is 60 km/h, and the speed on the ordinary road is 45 km/h. How much time do you save by taking the highway instead of the normal road?
务川县城到遵义的公路约长180千米．一辆汽车走高速路的平均速度是60千米/时，走普通公路的速度是45千米/时．走高速公路比普通公路节省多少时间？
<gadget id="calculator">180 / 45</gadget>
<output>4</output>

<gadget id="calculator">180 / 60</gadget>
<output>3</output>

<gadget id="calculator">4 - 3</gadget>
<output>1</output>

<result>1</result>