Aunt Zhang deposits 20,000 yuan in the bank for 2 years, and the annual interest rate is 3.87%. After the maturity, Aunt Zhang can get how much after-tax interest.
张阿姨把20000元存入银行，定期2年，年利率是3.87%，到期后张阿姨可以得到税后利息多少元．
<gadget id="calculator">3.87 / 100</gadget>
<output>0.0387</output>

<gadget id="calculator">20_000 * 0.0387 * 2</gadget>
<output>1_548</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">1_548 * (4/5)</gadget>
<output>6_192/5 = around 1_238.4</output>

<result>6_192/5 = around 1_238.4</result>