There are a batch of books in the school library. After lending out 40%, 360 new books are bought, and there are 5640 books left. How many books did the library have?
学校图书馆存有一批书，借出40%后，又买来新书360本，这时还有书5640本．图书馆原来有图书多少本？
<gadget id="calculator">5_640 - 360</gadget>
<output>5_280</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">5_280 / (3/5)</gadget>
<output>8_800</output>

<result>8_800</result>