project can be completed by team A in 30 days alone, and team B can complete the project in 5 days alone (1/4). After A and B work together for 3 days, B will do the rest alone. How many days will it take to complete?
一项工程，甲队独做30天完成，乙队独做5天完成这项工程的(1/4)．甲乙两人合做3天后，余下的由乙独做，还需要几天才能完成？
<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

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

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

<gadget id="calculator">(1/12) * 3</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">(3/4) / (1/20)</gadget>
<output>15</output>

<result>15</result>