Aunt Li’s monthly income is 4,000 yuan. According to national regulations, the portion exceeding 3,500 yuan has to pay 3% personal income tax. How much is Aunt Li’s income after personal income tax?
李阿姨每月收入4000元，按国家规定超过3500元的部分要缴纳3%个人所得税，李阿姨个人所得税后的收入是多少元．
<gadget id="calculator">4_200 - 3_500</gadget>
<output>700</output>

<gadget id="calculator">3 / 100</gadget>
<output>3/100 = around 0.03</output>

<gadget id="calculator">700 * (3/100)</gadget>
<output>21</output>

<gadget id="calculator">4_200 - 21</gadget>
<output>4_179</output>

<result>4_179</result>