Using a computer to enter a manuscript, A can complete it in 10 days alone, and B can complete it in 15 days alone. Now A and B are working together. Because B fell ill and rested for several days, it took 8 days to complete the task. So, how many days did B rest in the middle?
用计算机录入一份书稿，甲单独做10天可完成，乙单独做15天可以完成．现在由甲、乙二人合做，由于乙中途生病休息了若干天，结果一共用了8天才完成任务．那么，乙中途休息了多少天．
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/10) * 8</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/5) / (1/15)</gadget>
<output>3</output>

<gadget id="calculator">8 - 3</gadget>
<output>5</output>

<result>5</result>