Cars A and B leave oppositely from places A and B at the same time. After 3 hours, car A meets car B at a distance of 12 kilometers beyond the midpoint. Car A travels 54 kilometers per hour. How far apart?
甲、乙两车同时从A、B两地相对开出，经过3小时后，甲车在超过中点12千米处与乙车相遇，甲车每小时行54千米，A、B两地相距多远？
<gadget id="calculator">54 * 3</gadget>
<output>162</output>

<gadget id="calculator">162 - 12</gadget>
<output>150</output>

<gadget id="calculator">150 * 2</gadget>
<output>300</output>

<result>300</result>