A section of the road is 30 kilometers long. Team A completed it in 10 days alone, team B completed it in 15 days alone, and after the two teams worked together for 3 days, how many days will it take for the remaining team B to complete it alone?
一段路长30千米，甲队单独修10天完成，乙队单独修15天完成，两队合修3天后，剩下的乙独修，还需要几天可以完成？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

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

<gadget id="calculator">(1/6) * 3</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

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

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