Two cars, A and B, depart from Lianyungang at the same time, and drive to Shanghai via Nanjing. Car A travels 70 kilometers per hour, and car B travels 90 kilometers per hour. After 7 hours, car B arrives in Shanghai, how far is car A from Shanghai?
甲乙两辆汽车同时从连云港出发，途经南京开往上海．甲车每小时行70千米，乙车每小时行90千米．经过7小时，乙车到达上海，这时甲车离上海还有多远？
<gadget id="calculator">90 * 7</gadget>
<output>630</output>

<gadget id="calculator">70 * 7</gadget>
<output>490</output>

<gadget id="calculator">630 - 490</gadget>
<output>140</output>

<result>140</result>