Two people, A and B, ride bicycles from A and B at the same time, and they meet for the first time at a distance of 27 kilometers from B. After meeting, they continue to drive, and return immediately after reaching the destination. They meet again at 12 kilometers away from place A. How many kilometers are there between places A and B?
甲乙两人骑自行车分别从A，B两地同时相向而行，第一次两人在距离B地27千米处相遇，相遇后，两人继续行驶，到达目的地后又立即返回，在距离A地12千米处又相遇了，A，B两地相距多少千米．
<gadget id="calculator">27 * 3</gadget>
<output>81</output>

<gadget id="calculator">81 - 12</gadget>
<output>69</output>

<result>69</result>