project can be completed by A alone in 20 days. B alone to do 30 days to complete. In the middle, A asks for 2 days off, and B asks for several days off. It took 16 days from driving to completing the task, so how many days does B ask for leave?
一项工程，甲单独做20天完成．乙单独做30天完成．中途甲请假2天，乙请假若干天．从开到完成任务共用了16天，那么乙请假多少天？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">16 - 2</gadget>
<output>14</output>

<gadget id="calculator">(1/20) * 14</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">1 - (7/10)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(3/10) / (1/30)</gadget>
<output>9</output>

<gadget id="calculator">16 - 9</gadget>
<output>7</output>

<result>7</result>