It takes 15 days for team A to build a waterway, and 20 days for team B to do it alone. Team A works alone for 5 days, and then teams A and B will work together to complete the rest. How many days will it take to complete the construction?
建筑一条水坭路，甲队独做要15天，乙队独做要20天，甲队先独做5天后，剩下的再由甲、乙两队合做，还要多少天修完？
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/15) * 5</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</output>

<gadget id="calculator">1 / 20</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">(1/15) + (1/20)</gadget>
<output>7/60 = around 0.116667</output>

<gadget id="calculator">(2/3) / (7/60)</gadget>
<output>40/7 = around 5.714286</output>

<result>40/7 = around 5.714286</result>