The original price of a pair of leather shoes is 200 yuan, but now they are on sale at a 10% discount due to a seasonal promotion. How much cheaper can I buy this pair of leather shoes?
一双皮鞋原价200元，现因换季促销打九折出售，买这双皮鞋可便宜多少元？
<gadget id="calculator">90 / 100</gadget>
<output>9/10 = around 0.9</output>

<gadget id="calculator">1 - (9/10)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">200 * (1/10)</gadget>
<output>20</output>

<result>20</result>