Xiaohong has a book and has read 25% of the book. If she reads another 70 pages, the ratio of the number of pages she has read to the number of pages she has not read is 3:2. How many pages does this book have?
小红有一本书，已经读了全书的25%，如果再读70页，则已读的页数与未读的页数比是3：2，这本书一共有多少页．
<gadget id="calculator">3 + 2</gadget>
<output>5</output>

<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(3/5) - (1/4)</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">70 / (7/20)</gadget>
<output>200</output>

<result>200</result>