A project can be completed in 4 days by team A alone (1/5), and team B can be completed in 3 days by itself (1/10). Now team A will do 5 days first, and the rest will be done by teams A and B together. How long will it take? days done?
一项工程，甲队独做4天完成(1/5)，乙队独做3天完成(1/10)，现在甲队先做5天，余下的由甲乙两队合做，还需几天完成？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/5) / 4</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) * 5</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">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/10) / 3</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/20) + (1/30)</gadget>
<output>1/12 = around 0.083333</output>

<gadget id="calculator">(3/4) / (1/12)</gadget>
<output>9</output>

<result>9</result>