An express train and a slow train are traveling towards each other from places A and B at the same time, and meet at a distance of 48 kilometers from the center point after 4 hours. It is known that the express train travels 84 kilometers per hour. Find the distance between places A and B.
一辆快车和一辆慢车分别从甲、乙两地同时相向而行，4小时后距离中心点48千米处相遇，已知快车每小时行84千米，求甲、乙两地的距离．
<gadget id="calculator">84 * 4</gadget>
<output>336</output>

<gadget id="calculator">336 - 48</gadget>
<output>288</output>

<gadget id="calculator">288 * 2</gadget>
<output>576</output>

<result>576</result>