Sonny has been reading a book called "Crayon Shin-chan" for the past two days. Yesterday he read the whole book (2/5), and today he reads 42 pages, leaving exactly 25% of the book. How many pages does this "Crayon Shin-chan" have?
桑尼这两天在看一本叫《蜡笔小新》的书，昨天看了全书的(2/5)，今天看了42页，正好剩下全书的25%设看．这本《蜡笔小新》共有多少页？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (1/4) - (2/5)</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">42 / (7/20)</gadget>
<output>120</output>

<result>120</result>