Xiaohong reads a book. After reading it on the first day, the ratio of the number of pages she has read to the number of unread pages is 1:5. After reading another 30 pages on the second day, the ratio of the number of pages she has read to the number of unread pages becomes 3:5, how many pages does this book have?
小红读一本书，第一天读完后，已读的和未读的页数比是1：5，第二天又读了30页，已读的和未读的页数比变为3：5，问这本书有多少页？
<gadget id="calculator">3 + 5</gadget>
<output>8</output>

<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</output>

<gadget id="calculator">1 + 5</gadget>
<output>6</output>

<gadget id="calculator">1 / 6</gadget>
<output>1/6 = around 0.166667</output>

<gadget id="calculator">(3/8) - (1/6)</gadget>
<output>5/24 = around 0.208333</output>

<gadget id="calculator">30 / (5/24)</gadget>
<output>144</output>

<result>144</result>