The library of Yuhong Primary School has a wealth of books, among which story books account for about (1/7), and technology trees account for about (2/7). What percentage of the books in the library do the rest of the books account for?
育红小学图书馆拥有丰富的图书，其中故事书约占(1/7)，科技树约占(2/7)．剩下的其它书占图书馆存书的几分之几？
<gadget id="calculator">1 / 7</gadget>
<output>1/7 = around 0.142857</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">1 - (1/7) - (2/7)</gadget>
<output>4/7 = around 0.571429</output>

<result>4/7 = around 0.571429</result>