It takes 28 days for A to type a manuscript alone, and 20 days for A and B to type it together. Now after the two have worked together for 8 days, B will type the rest of the manuscript alone. How many days does B need to type to complete?
一部书稿，甲单独打需要28天完成，甲、乙两个打字员合打需20天完成．现在两人合打8天后，余下的书稿由乙单独打，乙需要打几天才能完成？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) * 8</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 / 28</gadget>
<output>1/28 = around 0.035714</output>

<gadget id="calculator">(1/20) - (1/28)</gadget>
<output>1/70 = around 0.014286</output>

<gadget id="calculator">(3/5) / (1/70)</gadget>
<output>42</output>

<result>42</result>