Uncle Li deposited 40% of his March salary of 20,000 yuan in the bank for 2 years, with an annual interest rate of 4.2%. How much can he withdraw from the bank at maturity? (To pay 5% interest tax)
李叔叔将三月份工资2万元的40%存入银行，定期2年，年利率是4.2%．到期时他共可从银行取出多少元？(要交纳5%的利息税)
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">20_000 * (2/5)</gadget>
<output>8_000</output>

<gadget id="calculator">4.2 / 100</gadget>
<output>0.042</output>

<gadget id="calculator">5 / 100</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">1 - (1/20)</gadget>
<output>19/20 = around 0.95</output>

<gadget id="calculator">8_000 * 0.042 * 2 * (19/20)</gadget>
<output>638.4</output>

<gadget id="calculator">8_000 + 638.4</gadget>
<output>8_638.4</output>

<result>8_638.4</result>