Xiao Ming reads an extra-curricular book on Saturday. When he reads 25 pages, it happens to be (5/9) of this book. How many pages does this book have?
星期六小明看一本课外书，当他看了25页，正好是这本书的(5/9)，这本书共有多少页？
<gadget id="calculator">5 / 9</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">25 / (5/9)</gadget>
<output>45</output>

<result>45</result>