Guangming Elementary School runs a factory to manufacture 4,500 sets of teaching aids, which is planned to be completed in 15 days. Actually, 75 more sets are made every day than the original plan. How many days will it take to complete the original production task?
光明小学校办工厂要制造4500套教具，计划15天做完．实际每天比原计划多做75套，完成原生产任务要多少天？
<gadget id="calculator">4_500 / 15</gadget>
<output>300</output>

<gadget id="calculator">75 + 300</gadget>
<output>375</output>

<gadget id="calculator">4_500 / 375</gadget>
<output>12</output>

<result>12</result>