If A and B have worked together for 12 days on a job, and A alone needs 12 days to do the rest, and B alone needs 15 days, how many days will it take A to complete the job alone?
一件工作，如果甲、乙两人合作了12天，剩下的由甲单独做还需12天，由乙单独做还需15天，这件工作全部由甲单独完成需多少天？
<gadget id="calculator">12 + 15 + 15</gadget>
<output>42</output>

<gadget id="calculator">12 / 42</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">1 - (2/7)</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">12 + 12</gadget>
<output>24</output>

<gadget id="calculator">(5/7) / 24</gadget>
<output>5/168 = around 0.029762</output>

<gadget id="calculator">1 / (5/168)</gadget>
<output>168/5 = around 33.6</output>

<result>168/5 = around 33.6</result>