Wang Rong deposits 500 yuan in the bank for a period of two years, with an annual interest rate of 2.15%. When it matures, how much after-tax interest can he get?
王荣将500元钱存入银行，定期二年，年利率是2.15%，到期时，他可得税后利息多少元．
<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">2.15 / 100</gadget>
<output>0.0215</output>

<gadget id="calculator">500 * (4/5) * 0.0215 * 2</gadget>
<output>17.2</output>

<result>17.2</result>