Two cars, A and B, drive towards each other at the same time from places A and B, which are 255 kilometers apart. The speed of car A is 45 km/h, and the speed of car B is 40 km/h. How many hours later will they meet?
甲、乙两辆汽车从相距255千米A、B两地同时相向开出，甲车的速度是45千米/时，乙车的速度是40千米/时，他们几小时后相遇？
<gadget id="calculator">45 + 40</gadget>
<output>85</output>

<gadget id="calculator">255 / 85</gadget>
<output>3</output>

<result>3</result>