Master Li is going to process 420 parts in 15 days. The task was actually completed 3 days ahead of schedule, how many parts are actually processed every day?
李师傅准备15天加工零件420个．实际提前3天完成了任务，实际每天多加工多少个零件？
<gadget id="calculator">15 - 3</gadget>
<output>12</output>

<gadget id="calculator">15 / 12</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">420 * (5/4)</gadget>
<output>525</output>

<result>525</result>