A bookstore buys a batch of books at a price of 10 yuan/book and sells them at a price of 12 yuan/book. When there are 100 books left in this batch of books, not only the full cost has been recovered, but also a profit of 100 yuan has been made. How many books are there in total?
某书店以10元/本的价格购进一批图书，并以12元/本的价格销售．当这批图书还剩下100本时，不仅收回了全部成本，还获利100元．这批图书共有多少本？
<gadget id="calculator">10 * 100</gadget>
<output>1_000</output>

<gadget id="calculator">1_000 + 100</gadget>
<output>1_100</output>

<gadget id="calculator">12 - 10</gadget>
<output>2</output>

<gadget id="calculator">1_100 / 2</gadget>
<output>550</output>

<gadget id="calculator">550 + 100</gadget>
<output>650</output>

<result>650</result>