The expressway from Beijing to Shanghai is 1,260 kilometers long. A passenger car and a truck start from two places at the same time and travel towards each other. The bus travels 100 kilometers per hour and the truck travels 70 kilometers per hour. After 7 hours, did the two cars meet?
北京到上海的高速公路全长1260千米．一辆客车和一辆货车同时从两地出发，相向而行，客车每小时行100千米，货车每小时行70千米．经过7小时，两车相遇了没有？
<result>7</result>