The teachers of the experimental primary school grouped and numbered the books in the library. The 3 teachers in group A compiled 280 books on average each, and the 2 teachers in group B compiled 300 books in total. How many volumes of books did the teachers of Group A and Group B compile on average?
实验小学老师在图书室对图书进行分组编号，甲组3位老师平均每人编好图书280册，乙组2位老师共编好图书300册．甲乙两组老师平均每组编好图书多少册？
<gadget id="calculator">280 * 3</gadget>
<output>840</output>

<gadget id="calculator">840 + 300</gadget>
<output>1_140</output>

<gadget id="calculator">1_140 / 2</gadget>
<output>570</output>

<result>570</result>