Two passenger and freight cars are driving towards each other from stations A and B at the same time, and meet at a distance of 12 kilometers from the midpoint. It is known that the speed ratio of the passenger and freight cars is 3:4. How many kilometers are the two stations A and B?
客货车两车同时从甲乙两站相向行驶，在距离中点12千米处相遇，已知客货两车速度比为3：4．甲乙两站相距多少千米？
<gadget id="calculator">3 + 4</gadget>
<output>7</output>

<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(4/7) - (3/7)</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">2 / (1/7)</gadget>
<output>14</output>

<gadget id="calculator">12 * 14</gadget>
<output>168</output>

<result>168</result>