The ratio of the speed of the truck to the speed of the passenger car is 3:4. The two cars drive from A and B at the same time and meet at a distance of 6 kilometers from the midpoint. How many kilometers are there between A and B?
货车速度与客车速度的比是3：4，两车同时从甲、乙两地相对开在离中点6千米处相遇．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">6 / (1/14)</gadget>
<output>84</output>

<result>84</result>