Read a book in 3 days. I read 80 pages on the first day, 1/4 of the whole book on the second day, and the sum of the previous two days on the third day. How many pages does this book have?
一本书分3天看完，第一天看了80页，第二天看了全书的(1/4)，第三天看的是前两天的和，这本书一共有多少页？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">(1/4) * 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">2 / (1/2)</gadget>
<output>4</output>

<gadget id="calculator">80 * 4</gadget>
<output>320</output>

<result>320</result>