The two masters and apprentices produced a batch of parts. The master does it alone for 8 hours, and the apprentice does it for 12 hours alone. After the two worked together for 3 hours, there were still 150 unfinished parts. How many parts are there in this batch?
师徒两人生产一批零件．师傅单独做8小时完成，徒弟单独做12小时完成．两人合做3小时后，还有150个没有完成，这批零件共有多少个？
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(1/8) + (1/12)</gadget>
<output>5/24 = around 0.208333</output>

<gadget id="calculator">(5/24) * 3</gadget>
<output>5/8 = around 0.625</output>

<gadget id="calculator">1 - (5/8)</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">150 / (3/8)</gadget>
<output>400</output>

<result>400</result>