The distance between A and B is 2500 kilometers. Two cars A and B start from A to B at the same time. After 4.2 hours, B leads A by 42 kilometers. It is known that A travels 70 kilometers per hour, and B travels per hour. How many kilometers?
A、B两地相距2500千米，甲、乙两辆汽车同时从A地出发开往B地，4.2小时后乙领先甲42千米，已知甲每小时行70千米，乙每小时行多少千米？
<gadget id="calculator">42 / 4.2</gadget>
<output>10</output>

<gadget id="calculator">70 - 10</gadget>
<output>60</output>

<result>60</result>