One piece of work is completed by A and B together (7/10), and the rest is done by A alone, and A takes 10.5 days in total; if it takes 15 days for A to do it alone, how many days does it take for B to do it alone?
一件工作甲乙合作完成了(7/10)，余下的甲单独做，甲共要10.5天；如果由甲独做要15天，由乙独做要多少天？
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/15) * 10.5</gadget>
<output>0.7</output>

<gadget id="calculator">1 - 0.7</gadget>
<output>0.3</output>

<gadget id="calculator">7 / 10</gadget>
<output>7/10 = around 0.7</output>

<gadget id="calculator">1 - (7/10)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">0.7 - (3/10)</gadget>
<output>0.4</output>

<gadget id="calculator">0.4 / (1/15)</gadget>
<output>6</output>

<gadget id="calculator">0.3 / 6</gadget>
<output>0.05</output>

<gadget id="calculator">1 / 0.05</gadget>
<output>20</output>

<result>20</result>