project can be completed by team A alone in 30 days, and team B alone in 20 days. If team B first works in 5 days and the rest is done jointly by team A and team B, how many days will it take for the two teams to finish?
一项工程，甲队单独做30天完成，乙队单独做20天完成，若乙队先做5天，其余的甲乙合做，两队还需多少天做完？
<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">(1/30) + (1/20)</gadget>
<output>1/12 = around 0.083333</output>

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

<result>9</result>