Zhang Xiaohong reads a story book. After reading a few pages, the ratio of what she has read to the rest is 1:4. After reading another 25 pages, the ratio of what she has read to the rest is 3:7. How many pages does this storybook have?
张小红看一本故事书，看了一些后，已看的与剩下的比是1：4，又看了25页，此时已看的与剩下的比是3：7．这本故事书共多少页？
<gadget id="calculator">3 + 7</gadget>
<output>10</output>

<gadget id="calculator">3 / 10</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 + 4</gadget>
<output>5</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(3/10) - (1/5)</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">25 / (1/10)</gadget>
<output>250</output>

<result>250</result>