A project can be completed by team A in 15 days alone, and team B in 20 days alone. Now the two teams work together for 5 days, and the rest will be completed by A alone. How many days will it take?
一项工程，甲队独干15天完成，乙队独干20天完成，现在由两队合作干5天后，还剩下的由甲单独完成，需要几天完成？
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/15) + (1/10)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/6) * 5</gadget>
<output>5/6 = around 0.833333</output>

<gadget id="calculator">1 - (5/6)</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(1/6) / (1/15)</gadget>
<output>5/2 = around 2.5</output>

<result>5/2 = around 2.5</result>