Two warships depart from two ports that are 688.5 kilometers apart at the same time. One warship travels 36.5 kilometers per hour, and the other warship travels 40 kilometers per hour. After how many hours did the two warships meet?
两艘军舰同时从相距688.5千米的两个港口相对开出，一艘军舰每小时行36.5千米，另一艘军舰每小时行40千米，经过几小时两艘军舰相遇？
<gadget id="calculator">36.5 + 40</gadget>
<output>76.5</output>

<gadget id="calculator">688.5 / 76.5</gadget>
<output>9</output>

<result>9</result>