Xiao Ming has read 20 pages of a story book, and just read the whole book (2/9). How many pages is this book?
一本故事书，小明同学已经看了20页，正好看了全书的(2/9)，这本书多少页？
<gadget id="calculator">2 / 9</gadget>
<output>2/9 = around 0.222222</output>

<gadget id="calculator">20 / (2/9)</gadget>
<output>90</output>

<result>90</result>