The distance between A and B is 480 kilometers. A truck travels from A to B at 60 kilometers per hour, and a bus travels from B to A at 80 kilometers per hour. The passenger car does not leave until one hour after the truck leaves, how many hours will it take for the two cars to meet?
甲、乙两地相距480千米，货车从甲地开往乙地，每小时行60千米，客车从乙地开往甲地，每小时行80千米．货车出发1小时后客车才出发，还要几小时两车相遇？
<gadget id="calculator">1 * 60</gadget>
<output>60</output>

<gadget id="calculator">480 - 60</gadget>
<output>420</output>

<gadget id="calculator">60 + 80</gadget>
<output>140</output>

<gadget id="calculator">420 / 140</gadget>
<output>3</output>

<result>3</result>