The school bought a batch of books. Among them, there are 56 story books, which happen to be science books (8/7), and there are fewer reference books than science books (2/7). How many reference books are there?
学校买来一批图书，其中故事书有56本，正好是科技书的(8/7)，工具书比科技书少(2/7)，工具书有多少本？
<gadget id="calculator">8 / 7</gadget>
<output>8/7 = around 1.142857</output>

<gadget id="calculator">56 / (8/7)</gadget>
<output>49</output>

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

<gadget id="calculator">1 - (2/7)</gadget>
<output>5/7 = around 0.714286</output>

<gadget id="calculator">49 * (5/7)</gadget>
<output>35</output>

<result>35</result>