computer company paid business tax at a rate of 20% in October, and the actual income after tax was 168,000 yuan. How much is the computer company's tax bill?
一家电脑公司，十月份按照20%的税率缴纳了营业税，税后的实际收入为16.8万元．这家电脑公司的纳税额是多少？
<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">16.8 / (4/5)</gadget>
<output>21</output>

<gadget id="calculator">21 * (1/5)</gadget>
<output>21/5 = around 4.2</output>

<result>21/5 = around 4.2</result>