When repairing a section of road, on the first day, (1/2) of the road is completed by 2 kilometers, and on the second day, the remaining (1/2) is repaired by 1 kilometer, and there are still 20 kilometers left to be completed. The length of the road.
修一段路，第一天修全路的(1/2)还多2千米，第二天修余下的(1/2)还少l千米，还剩下20千米没有修完，求公路全长．
<gadget id="calculator">20 - 1</gadget>
<output>19</output>

<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">19 / (1/2)</gadget>
<output>38</output>

<gadget id="calculator">38 + 2</gadget>
<output>40</output>

<gadget id="calculator">40 / (1/2)</gadget>
<output>80</output>

<result>80</result>