There are 400 science and technology books in the school, which are distributed to 5 grades on average, and each grade has 4 classes. How many books are distributed to each class on average?
学校有400本科技书，平均分给5个年级，每个年级有4个班，平均每个班分到多少本书？
<gadget id="calculator">400 / 5 / 4</gadget>
<output>20</output>

<result>20</result>