Xinhua Bookstore shipped 940 children's books, sold 18 packs, and left 220 books. How many books per pack?
新华书店运来儿童书籍940本，卖出18包，还剩220本，平均每包多少本？
<gadget id="calculator">940 - 220</gadget>
<output>720</output>

<gadget id="calculator">720 / 18</gadget>
<output>40</output>

<result>40</result>