There are 1,560 books in the school library, 840 books are donated to Hope Primary School, and the rest are lent to 24 classes. How many books do each class borrow on average?
学校图书室有书1560本，捐给希望小学840本，剩下的借给24个班，平均每个班借多少本？
<gadget id="calculator">1_560 - 840</gadget>
<output>720</output>

<gadget id="calculator">720 / 24</gadget>
<output>30</output>

<result>30</result>