Xinhua Bookstore shipped back a batch of literature and art books and science and technology books, of which literature and art books accounted for 5/7 of the total, 2100 more than science and technology books. How many palindromic art and technology books did Xinhua Bookstore ship?
新华书店运回一批文艺书和科技书，其中文艺书占总数的(5/7)，比科技书多2100本．新华书店运回文艺术和科技书一共多少本？
<gadget id="calculator">5 / 7</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">1 - (5/7)</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(5/7) - (2/7)</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">2_100 / (3/7)</gadget>
<output>4_900</output>

<result>4_900</result>