If A and B work together on a job for 6 days, the remaining work will take 10 days if A does it alone, and 15 days if B does it alone. If A alone does all the work, how many days will it take to complete it?
一项工作，甲乙两人合做6天后，余下的工作若让甲独做需要10天才能完成，若让乙独做需要15天才能完成．如果全部工作由甲独做，需要多少天完成？
<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>3/2 = around 1.5</output>

<gadget id="calculator">6 / (3/2)</gadget>
<output>4</output>

<gadget id="calculator">6 + 4 + 10</gadget>
<output>20</output>

<result>20</result>