For a road, 20% of the unrepaired road has been repaired, and another 6 kilometers have been repaired. At this time, 25% of the unrepaired road has been repaired. How many kilometers is this road?
一条公路，已修是未修的20%，又修了6千米，这时已修的是未修的25%，这条公路长多少千米？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

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

<gadget id="calculator">(1/5) - (1/6)</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">6 / (1/30)</gadget>
<output>180</output>

<result>180</result>