An extra-curricular book is 20 yuan, and it is now on sale with a 40% discount. How much is the price?
一本课外书20元，现六折出售，售价多少元．
<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">20 * (3/5)</gadget>
<output>12</output>

<result>12</result>