Xiaohong reads a science and technology book, and reads 25% of it on the first day, and the ratio of the number of pages she reads on the second day to that on the first day is 4:5, and she reads 72 pages in two days. How many pages does this book have?
小红读一本科技书，第一天读了25%，第二天读的页数与第一天的比是4：5，两天共读了72页．这本书有多少页？
<gadget id="calculator">25 / 100</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">4 / 5</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(1/4) * (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/4) + (1/5)</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">72 / (9/20)</gadget>
<output>160</output>

<result>160</result>