A project requires 10 hours for A alone, 12 hours for B, and 15 hours for C. After 3 hours of joint work, A and B leave with other tasks. How many hours will C be left to complete?
一项工程，单独做甲要10小时，乙要12小时，丙要15小时，三人合做3小时后，甲、乙另有任务离开，剩下的丙还要多少小时才能完成？
<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) * 3</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) / (1/15)</gadget>
<output>15/4 = around 3.75</output>

<result>15/4 = around 3.75</result>