There is a project that can be completed in 10 days by engineering team A alone, 12 days by engineering team B alone, and 15 days by project C alone. Now teams A, B, and C work together to complete the remaining project in 2 days. How many days does it take for C to complete it alone?
有一项工程，甲工程队单独做要10天完成，乙工程队单独做要12天完成，丙工程单独做要15天完成，现在甲、乙、丙三队合干2天剩下的工程再由丙单独干几天才能完成？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<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">(1/10) + (1/12) + (1/15)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) * 2</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>