batch of parts can be processed by A and B in 24 days. Now A alone can do it for 16 days, and then B can do it alone for another 12 days. There are still (2/5) of this batch of parts that have not been completed. How many days does it take for A to process this batch of parts alone?
加工一批零件，甲、乙合做24天可以完成，现在由甲先单独做16天，然后乙单独再做12天，还剩下这批零件的(2/5)没有完成．甲单独加工这批零件需要多少天？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 24</gadget>
<output>1/24 = around 0.041667</output>

<gadget id="calculator">(1/24) * 12</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (2/5) - (1/2)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">16 - 12</gadget>
<output>4</output>

<gadget id="calculator">(1/10) / 4</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">1 / (1/40)</gadget>
<output>40</output>

<result>40</result>