The toy factory produced 12,500 small racing cars for Children's Day. It was originally planned to be completed in 25 days. After 5 days of work, the technology was improved and the work efficiency was 4 times that of the original. In this way, this batch of racing cars can be completed a few days earlier than planned?
玩具厂为"六一"儿童节生产12500辆小赛车，原计划25天完成，工作5天后，改进了技术，工效是原来的4倍，这样这批赛车可比计划提前几天完工？
<gadget id="calculator">5 / 25</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 / 25</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">(1/25) * 4</gadget>
<output>4/25 = around 0.16</output>

<gadget id="calculator">(4/5) / (4/25)</gadget>
<output>5</output>

<gadget id="calculator">25 - 5 - 5</gadget>
<output>15</output>

<result>15</result>