A road was built in 3 days, 20% of the total length was built on the first day, 800 meters on the second day, and 100 meters less than the sum of the previous two days on the third day. How long is this road in meters?
3天修完一条路，第一天修了全长的20%，第二天修了800米，第三天修的比前两天的总和少100米，这条路全长多少米？
<gadget id="calculator">800 - 100</gadget>
<output>700</output>

<gadget id="calculator">800 + 700</gadget>
<output>1_500</output>

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

<gadget id="calculator">1 - (1/5) - (1/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1_500 / (3/5)</gadget>
<output>2_500</output>

<result>2_500</result>