A truck carries goods from point A to point B, returns empty, and continues to carry goods. When it is fully loaded, it will drive 40 kilometers per hour, and when it returns empty, it will drive 70 kilometers per hour. Not counting the loading time, it took a total of 5.5 hours. May I ask: How many kilometers is the distance between A and B?
一辆货车从甲地往乙地运货，然后空车返回，再继续运货．去的时候满载，每小时行驶40千米，回的时候空载，每小时行驶70千米．不算装载时间，总共花了5.5小时，请问：甲乙两地的距离是多少千米？
<gadget id="calculator">1 / 40</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">1 / 70</gadget>
<output>1/70 = around 0.014286</output>

<gadget id="calculator">(1/40) + (1/70)</gadget>
<output>11/280 = around 0.039286</output>

<gadget id="calculator">5.5 / (11/280)</gadget>
<output>140</output>

<result>140</result>