road construction team builds a road. The first time it built the full length (2/5), and the second time it repaired 20 kilometers. At this time, 20% of the total length remained unrepaired. How many kilometers is the total length of this road? ?
一个筑路队修一条公路，第一次修筑了全长的(2/5)，第二次修了20千米，这时还剩全长的20%没修，这条公路全长多少千米？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (2/5) - (1/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">20 / (2/5)</gadget>
<output>50</output>

<result>50</result>