The school library organizes science and literature books, among which science and technology books account for (3/10), and later bought 15 science and technology books, so that science and technology books account for the total (11/25), how many science and technology books are there? Book.
学校图书室对科技书和文艺书进行整理，其中科技书占(3/10)，后来又买来了15本科技书，这样科技书占总数的(11/25)，问原来科技书有多少本．
<gadget id="calculator">25 - 11</gadget>
<output>14</output>

<gadget id="calculator">11 / 14</gadget>
<output>11/14 = around 0.785714</output>

<gadget id="calculator">10 - 3</gadget>
<output>7</output>

<gadget id="calculator">3 / 7</gadget>
<output>3/7 = around 0.428571</output>

<gadget id="calculator">(11/14) - (3/7)</gadget>
<output>5/14 = around 0.357143</output>

<gadget id="calculator">15 / (5/14)</gadget>
<output>42</output>

<gadget id="calculator">42 * (3/7)</gadget>
<output>18</output>

<result>18</result>