The distance between A and B is 650 kilometers. Cars A and B drive from the two places at the same time. After 2.5 hours, the distance between the two cars is still 400 kilometers. How many hours will it take for the two cars to meet? (Solve with ratio)
甲乙两地相距650千米，甲乙两车同时从两地相对开出，2.5小时后两车还相距400千米，两车再行多少小时才能相遇？(用比例解决)
<gadget id="calculator">400 * 2.5</gadget>
<output>1_000</output>

<gadget id="calculator">650 - 400</gadget>
<output>250</output>

<gadget id="calculator">1_000 / 250</gadget>
<output>4</output>

<result>4</result>