Processing a batch of parts, master and apprentice alone, can be completed in 12 hours. Now the master-student cooperation, the apprentice makes 25 pieces every day, and the apprentice makes (1/4) of this batch of parts when the project is completed. How many parts are there in total?
加工一批零件，师徒独做，12小时可以完成．现在师徒合作，徒弟每天做25个，结果完工时徒弟做了这批零件的(1/4)，这批零件一共多少个？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (1/4)</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">(3/4) / (1/4)</gadget>
<output>3</output>

<gadget id="calculator">3 * 12 * 25</gadget>
<output>900</output>

<result>900</result>