To complete a project alone, A takes 10 days, B takes 15 days, and C takes 30 days. After A and B have cooperated for 3 days, A is transferred to another project, and C will take over A's work. How many days will it take to complete the task?
单独完成一项工程，甲需要10天，乙需要15天，丙需要30天．甲乙合作3天后，甲被调往其他工程，由丙来接替甲的工作，问还要几天才能完成任务？
<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 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/15) + (1/30)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/2) / (1/10)</gadget>
<output>5</output>

<result>5</result>