Mr. Zhao's monthly salary is 4,000 yuan, and the portion exceeding 3,500 yuan is subject to personal income tax at a rate of 3%. How much is Mr. Zhao's after-tax salary?
赵老师的月工资为4000元，按规定超出3500元的部分按3%的税率缴纳个人所得税．赵老师税后工资为多少元？
<gadget id="calculator">4_000 - 3_500</gadget>
<output>500</output>

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

<gadget id="calculator">500 * (3/100)</gadget>
<output>15</output>

<gadget id="calculator">4_000 - 15</gadget>
<output>3_985</output>

<result>3_985</result>