It takes 15 days for team A to do a project alone, and 10 days for team B to do it alone. If team A does 3 days first, and the rest is left to the cooperation of teams A and B, how many days will it take to complete?
一项工程甲队独做需要15天，乙队独做需要10天，如果甲队先做3天，剩下的由甲、乙两队合作，还需几天才能完成？
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/15) * 3</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</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">(4/5) / (1/6)</gadget>
<output>24/5 = around 4.8</output>

<result>24/5 = around 4.8</result>