The taxable income of Xiaohong’s father’s salary last month was 420 yuan. If the personal income tax is paid at a rate of 5%, how much personal income tax should be paid?
小红爸爸上月工资中应纳税所得额是420元，如果按5%的税率缴纳个人所得税，应缴纳个人所得税多少元？
<gadget id="calculator">5 / 100</gadget>
<output>1/20 = around 0.05</output>

<gadget id="calculator">420 * (1/20)</gadget>
<output>21</output>

<result>21</result>