Two cars drive from two cities A and B at the same time. Car A travels 35 kilometers per hour, and car B travels 55 kilometers per hour. After driving for 4 hours, the distance traveled by the two cars is the distance between the two cities. The distance is (5/7), how many kilometers is the distance between A and B?
两辆汽车从A、B两个城市同时相对开出，甲车每小时行35千米，乙车每小时行55千米，开车4小时后，两车走完的路程是两城之间的距离的(5/7)，A、B两城相距多少千米？
<gadget id="calculator">35 + 55</gadget>
<output>90</output>

<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">4 / (5/7)</gadget>
<output>28/5 = around 5.6</output>

<gadget id="calculator">90 * (28/5)</gadget>
<output>504</output>

<result>504</result>