Since January 1, 2006, the personal income tax standard has been changed from 800 yuan to 1,600 yuan, that is, the part of the salary exceeding 1,600 yuan will be taxed at 20%. Teacher Li's monthly salary is 1,800 yuan, so how much tax should Teacher Li pay every month?
自2006年1月1日起个人所得税标准由800元改为1600元，即工资超过1600元的那部分按20%缴纳税金．李老师每月工资是1800元，那么李老师每月应缴纳税金多少元．
<gadget id="calculator">1_800 - 1_600</gadget>
<output>200</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">200 * (1/5)</gadget>
<output>40</output>

<result>40</result>