A project can be completed in 20 days by team A alone, and by team B in 30 days. After 5 days by team A alone, how many days will it take for the remaining two teams to work together?
一项工程，甲队单独做需要20天完成，乙队单独完成需要30天完成，先由甲队单独做5天后，余下的两队合作，还需几天完成？
<gadget id="calculator">1 / 20</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 / 30</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>