The original price of a book is 40 yuan, and now it is on sale at a 15% discount. What is the current price?
一本书原价40元，现在打八五折出售，现价多少元．
<gadget id="calculator">85 / 100</gadget>
<output>17/20 = around 0.85</output>

<gadget id="calculator">40 * (17/20)</gadget>
<output>34</output>

<result>34</result>