The school library purchased a batch of books. The original plan was to allocate 100 books to each class, but actually 20 more books were allocated to each class. As a result, 5 classes in the sixth grade were not allocated books. How many books are there in total?
学校图书馆购进一批图书，原计划每班分100本，实际每班多分了20本，结果六年级5个班未分到图书．这批图书共有多少本？
<gadget id="calculator">100 * 5</gadget>
<output>500</output>

<gadget id="calculator">20 * 5</gadget>
<output>100</output>

<gadget id="calculator">500 + 100</gadget>
<output>600</output>

<gadget id="calculator">20 - 100</gadget>
<output>-80</output>

<gadget id="calculator">100 + (-80)</gadget>
<output>20</output>

<gadget id="calculator">600 / 20</gadget>
<output>30</output>

<gadget id="calculator">100 * 30</gadget>
<output>3_000</output>

<result>3_000</result>