A schoolbag is 85 yuan, if you get 20% off, how much can you save?
一个书包85元，如果打8折，可以节约多少元？
<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">85 * (1/5)</gadget>
<output>17</output>

<result>17</result>