(Example of solving equations) When Xiao Ming reads a book, the ratio of the number of pages he has read to the number of unread pages is 1:5. If he reads another 30 pages, the number of pages he has read and the number of unread pages is 3:5. How many pages does this book have?
(列方程解应用题)小明读一本书，已读与未读的页数比是1：5，如果再读30页，则已读和未读的页数为3：5．这本书共有多少页？
<gadget id="calculator">3 / 8</gadget>
<output>3/8 = around 0.375</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>