The distance between A and B is 360 km. A train of freight cars and a train of passenger cars leave from both places. How many hours will we meet?
甲乙两地相距360千米，一列货车和一列客车从甲、乙两地同时相对开出，已知客车的速度是每小时50千米，货车的速度是每小时40千米，两车开出后几小时相遇？
<gadget id="calculator">40 + 50</gadget>
<output>90</output>

<gadget id="calculator">360 / 90</gadget>
<output>4</output>

<result>4</result>