The road between A and B is 500 km long. Two passenger and freight vehicles leave from A and B oppositely at the same time. After 2 hours, the distance between the two vehicles is still 300 kilometers. According to this calculation, how many hours will it take for the two cars to meet?
甲、乙两地之间的公路长500千米．客、货两车同时从甲、乙两地相对开出，经过2小时两车还相距300千米．照这样计算，两车还要行多少小时才能相遇？
<gadget id="calculator">500 - 300</gadget>
<output>200</output>

<gadget id="calculator">200 / 2</gadget>
<output>100</output>

<gadget id="calculator">300 / 100</gadget>
<output>3</output>

<result>3</result>