When Li Wen read a book, he read 20% of the whole book on the first day, 48 pages on the second day, and exactly half of the book in two days. How many pages does this book have?
李文读一本书，第一天读了全书的20%，第二天读了48页，两天正好读了这本书的一半，这本书有多少页？
<gadget id="calculator">50 / 100</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">20 / 100</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">(1/2) - (1/5)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">48 / (3/10)</gadget>
<output>160</output>

<result>160</result>