The distance between A and B is 450 kilometers. A car starts from A and travels 50.5 kilometers per hour. A truck starts from B at the same time and travels 39.5 kilometers per hour. How many hours later will the two cars meet?
甲、乙两地相距450千米，汽车从甲地出发，每小时行50.5千米，货车同时从乙地出发，每小时行39.5千米．几小时后两车相遇？
<gadget id="calculator">50.5 + 39.5</gadget>
<output>90</output>

<gadget id="calculator">450 / 90</gadget>
<output>5</output>

<result>5</result>