It takes 25 days for the master to process a batch of parts, and 30 days for the apprentice to complete it. It is known that the master processes 3 more parts per day than the apprentice, so how many parts are there in total?
加工一批零件，师傅做需要25天完成，徒弟做需要30天完成，已知师傅比徒弟每天多加工3个零件，那么这批零件一共有多少个？
<gadget id="calculator">1 / 25</gadget>
<output>1/25 = around 0.04</output>

<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/25) - (1/30)</gadget>
<output>1/150 = around 0.006667</output>

<gadget id="calculator">3 / (1/150)</gadget>
<output>450</output>

<result>450</result>