From A to B, the uphill road accounts for (7/18), the flat road accounts for (4/9), and the downhill road accounts for (1/6). A car makes a round trip, and the downhill road covers a total of 20 kilometers. How many kilometers is the distance between A and B?
从甲地到乙地，上坡路占(7/18)，平坦路占(4/9)，下坡路占(1/6)，一辆汽车往返一趟，下坡路共走了20千米．甲乙两地之间的路程的多少千米？
<gadget id="calculator">7 / 18</gadget>
<output>7/18 = around 0.388889</output>

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

<gadget id="calculator">(7/18) + (1/6)</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">20 / (5/9)</gadget>
<output>36</output>

<result>36</result>