Xinhua Bookstore shipped a batch of books, sold 32% of the books on the first day, and sold 45% of the books on the second day. It is known that 640 books were sold on the first day, how many books were sold in two days.
新华书店运来一批图书，第一天卖出这批图书的32%，第二天卖出这批图书的45%，已知第一天卖出640本，两天一共卖出多少本．
<gadget id="calculator">32 / 100</gadget>
<output>8/25 = around 0.32</output>

<gadget id="calculator">640 / (8/25)</gadget>
<output>2_000</output>

<gadget id="calculator">45 / 100</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">2_000 * (9/20)</gadget>
<output>900</output>

<gadget id="calculator">900 + 640</gadget>
<output>1_540</output>

<result>1_540</result>