Mr. Li deposited 400 yuan in the bank, fixed deposit and withdrawal for 4 years, with an annual interest rate of 2.80%. How much after-tax interest can Mr. Li get when it expires? (Deposit interest tax is taxed at 20%)
李老师把400元钱存入银行，定期整存整取4年，年利率2.80%．到期时李老师可得税后利息多少元？(存款利息税按20%纳税)
<gadget id="calculator">2.8 / 100</gadget>
<output>0.028</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">400 * 0.028 * 4 * (4/5)</gadget>
<output>35.84</output>

<result>35.84</result>