Two cars A and B leave opposite stations A and B at the same time. The two cars meet for the first time at a distance of 30 kilometers from Station A. After the meeting, the two cars continue to drive. Go back the same way and meet for the second time at a distance of 12 kilometers from station B. How many kilometers are there between stations A and B?
A、B两辆汽车同时从甲、乙两站相对开出，两车第一次在距甲站30千米处相遇，相遇后两车继续行驶，各自到达乙、甲两站后，立即沿原路返回，第二次在距乙站12千米处相遇，甲、乙两站间相距多少千米．
<gadget id="calculator">30 * 3</gadget>
<output>90</output>

<gadget id="calculator">90 - 12</gadget>
<output>78</output>

<result>78</result>