The distance between A and B is 650 kilometers. Two cars, A and B, drive in opposite directions from the two places at the same time. After driving for 2.5 hours, the distance between the two cars is 400 kilometers. According to this calculation, how many hours will it take for the two cars to meet each other?
A、B两地相距650千米，甲乙两辆汽车分别从两地同时相向开出，行驶了2.5小时，两车还相距400千米，照这样计算，两车再行多少小时才能相遇？
<gadget id="calculator">650 - 400</gadget>
<output>250</output>

<gadget id="calculator">250 / 2.5</gadget>
<output>100</output>

<gadget id="calculator">400 / 100</gadget>
<output>4</output>

<result>4</result>