The number of literature books (2/7) and reference books (4/9) in the library of Peiyou Primary School are equal. There are 2800 literature books, but how many reference books are there?
培优小学图书室里文学书的(2/7)和工具书的(4/9)相等，文学书有2800本，工具书有多少本？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">4 / 9</gadget>
<output>4/9 = around 0.444444</output>

<gadget id="calculator">(2/7) / (4/9)</gadget>
<output>9/14 = around 0.642857</output>

<gadget id="calculator">2_800 * (9/14)</gadget>
<output>1_800</output>

<result>1_800</result>