When Xiao Ming reads a book, the ratio of pages he has read to pages he has not read is 2:5. If you read 33 more pages, the ratio of the number of pages read to unread is 5:7. How many pages does this book have?
小明读一本书，已读和未读的页数比是2：5．如果再读33页，则已读和未读的页数比是5：7．这本书一共有多少页？
<gadget id="calculator">5 + 7</gadget>
<output>12</output>

<gadget id="calculator">5 / 12</gadget>
<output>5/12 = around 0.416667</output>

<gadget id="calculator">2 + 5</gadget>
<output>7</output>

<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

<gadget id="calculator">(5/12) - (2/7)</gadget>
<output>11/84 = around 0.130952</output>

<gadget id="calculator">33 / (11/84)</gadget>
<output>252</output>

<result>252</result>