Huiwen Bookstore sold a batch of books at a discount. On the first day, 40% of the books were sold, and another 600 books were sold on the second day. At this time, the ratio of the number of books sold to the number of books that were not sold was 11:4. How many books are there in total?
汇文书店优惠出售一批图书，第一天卖了这批图书的40%，第二天又卖了600本，这时已经卖出的本数和没有卖的本数之比是11：4，这批图书共有多少本？
<gadget id="calculator">11 + 4</gadget>
<output>15</output>

<gadget id="calculator">11 / 15</gadget>
<output>11/15 = around 0.733333</output>

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

<gadget id="calculator">(11/15) - (2/5)</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">600 / (1/3)</gadget>
<output>1_800</output>

<result>1_800</result>