Two trains are running towards each other from A and B. The slow train takes 8 hours to go from A to B, which is one-third longer than the fast train from B to A. If two trucks leave at the same time, the express train travels 40 kilometers longer than the slow train when they meet. What is the distance between A and B in kilometers?
两列火车从甲、乙两地相向而行，慢车从甲地到乙地需8时，比快车从快车从乙地到甲地多用三分之一的时间．如果两货车同时开出，那么相遇时快车比慢车多行40千米．甲、乙两地的距离为多少千米．
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 + (1/3)</gadget>
<output>4/3 = around 1.333333</output>

<gadget id="calculator">8 / (4/3)</gadget>
<output>6</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">(1/6) + (1/8)</gadget>
<output>7/24 = around 0.291667</output>

<gadget id="calculator">1 / (7/24)</gadget>
<output>24/7 = around 3.428571</output>

<gadget id="calculator">(1/6) * (24/7)</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">1 - (4/7)</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">40 / (1/7)</gadget>
<output>280</output>

<result>280</result>