A certain engineering team repaired a section of road, originally planned to repair 3.2km per day, and completed it in 20 days, but actually repaired 0.8km more per day, so how many days can the repair be completed in advance?
某工程队修一段公路，原计划每天修3.2km，20天完成，实际每天多修0.8km，这样可以提前几天修完？
<gadget id="calculator">3.2 + 0.8</gadget>
<output>4</output>

<gadget id="calculator">20 / 4</gadget>
<output>5</output>

<gadget id="calculator">3.2 * 5</gadget>
<output>16</output>

<gadget id="calculator">20 - 16</gadget>
<output>4</output>

<result>4</result>