A project can be completed by teams A, B, and C individually in 10 days, 12 days, and 15 days. Teams B and C cooperate for 3 days, and team B leaves due to an accident and is replaced by team A. The work efficiency remains the same. Under the circumstances, how many days to complete this project?
一件工程，甲、乙、丙队单独做各要10天、12天、15天才能完成，乙、丙先合作3天后，乙队因事离去，由甲队代替，工作效率都不变的情况下，几天完成此项工程？
<gadget id="calculator">1 / 12</gadget>
<output>1/12 = around 0.083333</output>

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

<gadget id="calculator">(1/12) + (1/15)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">(3/20) * 3</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">1 - (9/20)</gadget>
<output>11/20 = around 0.55</output>

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

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

<gadget id="calculator">(11/20) / (1/6)</gadget>
<output>33/10 = around 3.3</output>

<gadget id="calculator">(33/10) + 3</gadget>
<output>63/10 = around 6.3</output>

<result>63/10 = around 6.3</result>