Xiaohong bought a copy of "Happy Composition" and a copy of "One Hundred Thousand Whys", which cost a total of 28.5 yuan.
小红买一本《快乐作文》和一本《十万个为什么》，一共花去28.5元，一本《快乐作文》2.7元，一本《十万个为什么》多少元？
<gadget id="calculator">28.5 - 2.7</gadget>
<output>25.8</output>

<result>25.8</result>