A project can be completed in 10 days by A alone, 8 days by B alone, and 4 days after A and B work together, how many days will it take for A to do it alone?
一项工程甲独做10天完成，乙独做8天完成，甲、乙合做4天后，剩下由甲独做还需多少天？
<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">(1/10) + (1/8)</gadget>
<output>9/40 = around 0.225</output>

<gadget id="calculator">(9/40) * 4</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">1 - (9/10)</gadget>
<output>1/10 = around 0.1</output>

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

<result>1</result>