An engineering team laid a section of sewer, originally planned to lay 20 meters per day, and completed it in 15 days. The actual paving is 5 meters more every day, and how many days have the actual task been completed? (Solve with ratio)
某工程队铺设一段下水道，原计划每天铺设20米，15天完成．实际每天多铺5米，实际多少天完成了任务？(用比例解)
<gadget id="calculator">20 * 15</gadget>
<output>300</output>

<gadget id="calculator">20 + 5</gadget>
<output>25</output>

<gadget id="calculator">300 / 25</gadget>
<output>12</output>

<result>12</result>