Li Yun's mother's monthly salary is 4,200 yuan. According to the provisions of the Individual Income Tax Law, the balance after deducting 3,500 yuan from monthly salary income is subject to individual income tax at a rate of 5%. How much personal income tax should Li Yun's mother pay each month?
李芸母亲的月工资是4200元．按个人所得税法的规定，每月工资收入扣除3500元后的余额部分，按5%的比例缴纳个人所得税．李芸的母亲每月应缴纳个人所得税多少元？
<gadget id="calculator">4_200 - 3_500</gadget>
<output>700</output>

<gadget id="calculator">5 / 100</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">700 * (1/20)</gadget>
<output>35</output>

<result>35</result>