Xiaohong reads a story book. She reads (1/10) on the first day and 30 pages on the second day. At this time, the ratio of the number of pages she has read to the number of remaining pages is 3:7. How many pages are there in this book? ?
小红读一本故事书，第一天读了(1/10)，第二天读了30页，这时已读的与剩下页数的比是3：7，这本书有多少页？
<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 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(3/10) - (1/10)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">30 / (1/5)</gadget>
<output>150</output>

<result>150</result>