Xiaohong read 45 pages of an extracurricular book, which happens to be (5/9) of this book. How many pages does this extracurricular book have?
一本课外读物，小红看了45页，正好是这本书的(5/9)，这本课外书一共有多少页？
<gadget id="calculator">5 / 9</gadget>
<output>5/9 = around 0.555556</output>

<gadget id="calculator">45 / (5/9)</gadget>
<output>81</output>

<result>81</result>