Xiao Ming and his sister go to the bookstore together, the sister buys an "English Dictionary" for 87 yuan, and Xiao Ming buys a science and technology book for 24 yuan. My sister paid the cashier 150 yuan, how much should I get back?
小明和姐姐一道去书店，姐姐买一本《英语辞典》用去87元，小明买一本科技类的书用去24元．姐姐付给收银员150元，应找回多少元？
<gadget id="calculator">87 + 24</gadget>
<output>111</output>

<gadget id="calculator">150 - 111</gadget>
<output>39</output>

<result>39</result>