A project can be completed by A alone in 10 days and by B in 15 days. Now B will do it in 3 days and A will continue to finish it. How many days will A need?
一项工程，甲独做10天完成，乙独做15天完成．现在由乙做3天后改由甲接着做完，甲还要多少天？
<gadget id="calculator">1 / 15</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">(1/15) * 3</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(4/5) / (1/10)</gadget>
<output>8</output>

<result>8</result>