A and B are walking towards each other at the same time from A and B respectively. When A has traveled 42 kilometers, B has just completed (1/3) of the distance between A and B. At this time, the distance between the two is 12 What is the distance in kilometers between A and B?
甲、乙两人分别从A、B两地同时相向而行，当甲走出42千米时，乙恰好走完了A、B两地之间距离的(1/3)，此时两人相距12千米，则A、B两地之间距离为多少千米．
<gadget id="calculator">42 + 12</gadget>
<output>54</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">54 / (2/3)</gadget>
<output>81</output>

<result>81</result>