A batch of parts, a technician and 2 apprentices need 12 days to complete, 2 technicians and 1 apprentice need 8 days to complete, how many days does it take for an apprentice to do it alone?
一批零件，一个技师和2个徒弟需要12天完成，2个技师和1个学徒需要8天完成，问一个学徒单独做需要多少天？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">(1/8) - (1/12)</gadget>
<output>1/24 = around 0.041667</output>

<gadget id="calculator">(1/12) - (1/24)</gadget>
<output>1/24 = around 0.041667</output>

<gadget id="calculator">1 + 2</gadget>
<output>3</output>

<gadget id="calculator">(1/24) / 3</gadget>
<output>1/72 = around 0.013889</output>

<gadget id="calculator">1 / (1/72)</gadget>
<output>72</output>

<result>72</result>