The original price of a suit is 210 yuan, how much will the price be reduced after a 20% discount.
一套西服原价210元，打八折后降价多少元．
<gadget id="calculator">80 / 100</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">1 - (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">210 * (1/5)</gadget>
<output>42</output>

<result>42</result>