Master Wang had to process 3,000 parts. After processing 1,500 parts, he improved his working method. It took only 12 hours to process the rest of the parts. On average, he processed 25 more parts per hour than before. How many hours did Master Wang spend processing these 3000 parts?
王师傅要加工3000个零件，加工了1500个以后改进了工作方法，加工剩下的零件只用了12小时，平均每小时比以前多加工了25个零件．王师傅加工这3000个零件共用多少小时．
<gadget id="calculator">3_000 - 1_500</gadget>
<output>1_500</output>

<gadget id="calculator">1_500 / 12</gadget>
<output>125</output>

<gadget id="calculator">125 - 25</gadget>
<output>100</output>

<gadget id="calculator">1_500 / 100</gadget>
<output>15</output>

<gadget id="calculator">12 + 15</gadget>
<output>27</output>

<result>27</result>