Xiaoli reads a book. She reads the whole book (4/7) in the first week, and reads 72 pages in the second week. At this time, the ratio of the number of pages read to the number of pages in the book is 4:5. This book has how many pages
小丽看一本书，第一周看了全书的(4/7)，第二周又看了72页，这时已看页数和全书页数的比是4：5，这本书有多少页？
<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">4 / 7</gadget>
<output>4/7 = around 0.571429</output>

<gadget id="calculator">(4/5) - (4/7)</gadget>
<output>8/35 = around 0.228571</output>

<gadget id="calculator">72 / (8/35)</gadget>
<output>315</output>

<result>315</result>