A batch of parts can be completed by A in 8 hours alone. After 2 hours, A and B cooperate for another 4 hours to complete the task. How many hours does it take for B to complete this batch of parts alone?
一批零件，甲单独做8小时完成，甲做2小时后，甲、乙二人又合作了4小时完成任务，乙单独做完成这批零件需要几小时？
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">(1/8) * 2</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) / 4</gadget>
<output>3/16 = around 0.1875</output>

<gadget id="calculator">(3/16) - (1/8)</gadget>
<output>1/16 = around 0.0625</output>

<gadget id="calculator">1 / (1/16)</gadget>
<output>16</output>

<gadget id="calculator">1 / 16</gadget>
<output>1/16 = around 0.0625</output>

<result>1/16 = around 0.0625</result>