The distance between the two cities is 600 kilometers. Two passenger and freight cars are driving toward each other from the two places at the same time. The passenger car travels 70 kilometers per hour, and the truck travels 80 kilometers per hour. How many hours will the two cars meet?
两城相距600千米，客货两车同时从两地相向而行，客车每小时行驶70千米，货车每小时行驶80千米，几小时两车相遇？
<gadget id="calculator">70 + 80</gadget>
<output>150</output>

<gadget id="calculator">600 / 150</gadget>
<output>4</output>

<result>4</result>