The bookstore shipped in a batch of books, sold 280 books on the first day, sold (1/4) more than the first day on the second day, and left (2/7) of the total number, how many books in this batch?
书店运进一批书，第一天卖出280本，第二天比第一天多卖(1/4)，还剩下总数的(2/7)，这批书共多少本？
<gadget id="calculator">240 + 300</gadget>
<output>540</output>

<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">540 / (4/7)</gadget>
<output>945</output>

<result>945</result>