The road from a certain county to the provincial capital is 180 kilometers long. A car travels at 90 km/h on a freeway and at 60 km/h on an ordinary road. How much time is saved by taking the expressway from the county seat to the provincial capital compared with ordinary roads?
某县城到省城的公路长180千米．一辆汽车走高速公路的速度是90千米/小时，走普通公路的速度是60千米/小时．从县城到省城走高速公路比普通公路节省多少时间？
<gadget id="calculator">180 / 60</gadget>
<output>3</output>

<gadget id="calculator">180 / 90</gadget>
<output>2</output>

<gadget id="calculator">3 - 2</gadget>
<output>1</output>

<result>1</result>