Xiao Ming bought two books, "Grimm's Fairy Tales" for 18.5 yuan, and "Xinhua Dictionary" for 11.3 yuan. Xiao Ming paid 50 yuan, how much should I get back?
小明买了两本书，《格林童话》18.5元，《新华字典》11.3元，小明付出50元，应找回多少钱？
<gadget id="calculator">50 - 18.5 - 11.3</gadget>
<output>20.2</output>

<result>20.2</result>