The road repair team repaired a section of the road. The original plan was to repair 1.2km a day, and it was completed in 15 days. The actual repair was 1.5km a day. In this way, how many days can the task be completed in advance?
修路队修一段路，原计划每天修1.2km，15天完成，实际每天修1.5km，这样，实际可以提前几天完成任务？
<gadget id="calculator">15 / 1.5</gadget>
<output>10</output>

<gadget id="calculator">1.2 * 10</gadget>
<output>12</output>

<gadget id="calculator">15 - 12</gadget>
<output>3</output>

<result>3</result>