The ratio of the speed of the truck to the speed of the passenger car is 3:4, and the two cars depart from Station A and Station B at the same time, and meet at a distance of 18km from the midpoint of the two stations. How many kilometers are there between A and B?
货车速度与客车的速度比是3：4，两车同时从甲、乙两站相对开出，在离两站中点18km处相遇．甲乙两地相距多少千米？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">3 + 4</gadget>
<output>7</output>

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

<gadget id="calculator">(1/2) - (3/7)</gadget>
<output>1/14 = around 0.071429</output>

<gadget id="calculator">18 / (1/14)</gadget>
<output>252</output>

<result>252</result>