Xiao Ming reads a book. He reads 15 pages on the first day and the rest (1/4) on the second day. At this time, the ratio of unread pages to read pages is 6:5. How many pages are there in this book? Page?
小明读一本书，第一天读了15页，第二天读了余下的(1/4)，这时，未读的与已读的页数比是6：5，这本书共有几页？
<gadget id="calculator">15 * 5</gadget>
<output>75</output>

<gadget id="calculator">15 * 6</gadget>
<output>90</output>

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

<gadget id="calculator">15 * (1/4) * 5</gadget>
<output>75/4 = around 18.75</output>

<gadget id="calculator">15 * (1/4) * 6</gadget>
<output>45/2 = around 22.5</output>

<gadget id="calculator">90 - (75/4) - (45/2)</gadget>
<output>195/4 = around 48.75</output>

<gadget id="calculator">75 + (195/4)</gadget>
<output>495/4 = around 123.75</output>

<gadget id="calculator">(1/4) * 5</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">(1/4) * 6</gadget>
<output>3/2 = around 1.5</output>

<gadget id="calculator">5 - (5/4) - (3/2)</gadget>
<output>9/4 = around 2.25</output>

<gadget id="calculator">(495/4) / (9/4)</gadget>
<output>55</output>

<result>55</result>