To build a road, the plan is to build 400 meters per day, but the actual daily repair is 25% more than the original plan. It actually took 20 days to complete the repair. How many days did the original plan take to complete the repair?
修一条公路，计划每天修400米，实际每天比原计划多修25%，实际用了20天修完，原计划要多少天修完？
<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">400 * (6/5)</gadget>
<output>480</output>

<gadget id="calculator">20 / 400</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">480 * (1/20)</gadget>
<output>24</output>

<result>24</result>