Xiao Ming and Xiao Liang read a story book together, and they have already read (1/4) of the whole book. If they read 15 more pages, the ratio of the number of pages they have read to the number of pages they have not read is 2:3. This story book How many pages are there?
小明和小亮一起看一本故事书，已经看了全书的(1/4)，如果再看15页，则看过的页数与未看的页数比是2：3，这本故事书一共有多少页？
<gadget id="calculator">2 + 3</gadget>
<output>5</output>

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

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

<gadget id="calculator">(2/5) - (1/4)</gadget>
<output>3/20 = around 0.15</output>

<gadget id="calculator">15 / (3/20)</gadget>
<output>100</output>

<result>100</result>