A project can be completed in 30 days alone, and can be completed in 10 days alone. Now the two work together for 5 days, and B goes. How many days will A need to complete? (column equation solution)
一项工程，甲单独做30天完成，以单独做10天完成，现在两人一起做了5天，乙去，问甲还需要几天完成？(列方程解答)
<gadget id="calculator">1 / 30</gadget>
<output>1/30 = around 0.033333</output>

<gadget id="calculator">(1/30) * 5</gadget>
<output>1/6 = around 0.166667</output>

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

<gadget id="calculator">(1/10) * 5</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/6) - (1/2)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(1/3) / (1/30)</gadget>
<output>10</output>

<result>10</result>