A paving team paved a section of road. It was originally planned to pave 3.2 kilometers per day and finish paving in 15 days. The actual pavement is 25% more than the original plan every day, so how many days can the road be paved in advance? (problems with proportions)
一个铺路队铺一段公路，原计划每天铺3.2千米，15天铺完．实际每天比原计划多铺25%，这样可提前几天铺完这段公路？(用比例解题)
<gadget id="calculator">3.2 * 15</gadget>
<output>48</output>

<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">3.2 * (1/4) * 15</gadget>
<output>12</output>

<gadget id="calculator">12 - 48</gadget>
<output>-36</output>

<gadget id="calculator">48 + (-36)</gadget>
<output>12</output>

<gadget id="calculator">3.2 * (1/4)</gadget>
<output>0.8</output>

<gadget id="calculator">3.2 + 0.8</gadget>
<output>4</output>

<gadget id="calculator">12 / 4</gadget>
<output>3</output>

<result>3</result>