The original price of a set of popular science books is 200 yuan, and it is sold at a 15% discount on the June 1st promotion. How much cheaper is it to buy this set of popular science books now?
一套科普书原价200元，六一节促销打8.5折出售，现在买这一套科普书可便宜多少元？
<gadget id="calculator">85 / 100</gadget>
<output>17/20 = around 0.85</output>

<gadget id="calculator">1 - (17/20)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">200 * (3/20)</gadget>
<output>30</output>

<result>30</result>