To build a canal, 500 meters per day, 50% of the whole process was repaired in 5 days, and the remaining work efficiency increased by 20%. How many days earlier can the remaining part of the project be completed?
修一条水渠，每天修500米，5天修了全程的50%，剩下的工作效率提高了20%，剩下这段工程可以提前多少天完工？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">500 * (6/5)</gadget>
<output>600</output>

<gadget id="calculator">5 / 600</gadget>
<output>1/120 = around 0.008333</output>

<gadget id="calculator">500 * (1/120)</gadget>
<output>25/6 = around 4.166667</output>

<gadget id="calculator">5 - (25/6)</gadget>
<output>5/6 = around 0.833333</output>

<result>5/6 = around 0.833333</result>