Two trains A and B depart from Jinan and Qingdao respectively at the same time and meet each other 4 hours later. It is known that car A travels 105 kilometers per hour and car B travels 95 kilometers per hour. How many kilometers are there between Jinan and Qingdao?
甲乙两列火车分别从济南和青岛同时相对开出，4小时后相遇．已知甲车每小时行105千米，乙车每小时行95千米．济南和青岛相距多少千米？
<gadget id="calculator">105 + 95</gadget>
<output>200</output>

<gadget id="calculator">200 * 4</gadget>
<output>800</output>

<result>800</result>