It takes 20 days for the master to make a batch of parts, and 30 days for the apprentice to make it alone. Now the master and apprentice work together for 5 days. How many days will it take for the remaining apprentices to complete it alone?
一批零件，师傅独做要20天，徒弟独做要30天，现在师徒合做5天，余下的徒弟一人独做还要多少天才能完成？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</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">(1/12) * 5</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">1 - (5/12)</gadget>
<output>7/12 = around 0.583333</output>

<gadget id="calculator">(7/12) / (1/30)</gadget>
<output>35/2 = around 17.5</output>

<result>35/2 = around 17.5</result>