As shown in the picture, in the activity of "Love Yushu and Dedication of Love", students in grades 1-3 of a certain school actively donated books to students in the disaster area. They donated 768 books in total. There are 2 classes in each grade, how many books are donated by each class on average?
如图，在"情系玉树奉献爱心"活动中，某校1-3年级的学生积极为灾区同学捐书，他们共捐了768本书．每个年级有2个班，平均每个班的同学捐了多少本书？
<gadget id="calculator">768 / 3 / 2</gadget>
<output>128</output>

<result>128</result>