It is known that the distance between the two cities is 688 kilometers. Two cars A and B drive from the two cities at the same time. Car A travels 80 kilometers per hour, and car B travels 92 kilometers per hour. How many hours will the two cars meet?
已知两城市相距688千米，A、B两车分别从两城市同时相对开出，A车每小时行80千米，B车每小时行92千米．几小时后两车能相遇？
<gadget id="calculator">80 + 92</gadget>
<output>172</output>

<gadget id="calculator">688 / 172</gadget>
<output>4</output>

<result>4</result>