An engineering team can repair 1,200 kilometers of roads in 20 days, and actually completed 20% of the road in the first 3 days. According to this calculation, how many days can the task be completed in advance?
某工程队20天能修1200千米的公路，实际前3天就完成了20%，照这样计算，可提前几天完成任务？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/5) / 3</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">1_200 * (1/15)</gadget>
<output>80</output>

<gadget id="calculator">1_200 / 80</gadget>
<output>15</output>

<gadget id="calculator">20 - 15</gadget>
<output>5</output>

<result>5</result>