When Xiaoliang reads a book, the ratio of pages he has read to pages he has not read is 2:3. If he reads 15 more pages, the ratio of pages he has read to pages he has not read is 3:2. This book has a total of how many pages
小亮看一本书，已看的与未看的页数的比是2：3，如果再看15页，则已看的与未看的页数的比是3：2，这本书共有多少页？
<gadget id="calculator">3 / 5</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">(3/5) - (2/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">15 / (1/5)</gadget>
<output>75</output>

<result>75</result>