A certain project is completed in 20 days by teams A and B, and by team A in 30 days alone. Now after the two teams work together for 15 days, Team A will finish the rest. How many days will it take?
某项工程，甲乙两队合做20天完成，甲队单独做30天完成．现在两队合做15天后，余下的由甲队完成，还要多少天？
<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/20) * 15</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/4) / (1/30)</gadget>
<output>15/2 = around 7.5</output>

<result>15/2 = around 7.5</result>