Lele reads a book, read (1/3) of this book on the first day, and (2/5) of this book on the second day, and read 15 pages less on the first day than on the second day. How many pages are there in this book?
乐乐读一本书，第一天读了这本书的(1/3)，第二天读了这本书的(2/5)，第一天比第二天少读15页．这本书一共多少页？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">(2/5) - (1/3)</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">15 / (1/15)</gadget>
<output>225</output>

<result>225</result>