Xiaohong reads a story book. She reads (2/7) of this book on the first day, and (1/3) of this book on the second day. There are still 80 pages left. How many pages are there in this book? Page?
小红看一本故事书，第一天看了这本书的(2/7)，第二天看了这本书的(1/3)，还剩80页没看，这本书共有多少页？
<gadget id="calculator">2 / 7</gadget>
<output>2/7 = around 0.285714</output>

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

<gadget id="calculator">1 - (2/7) - (1/3)</gadget>
<output>8/21 = around 0.380952</output>

<gadget id="calculator">80 / (8/21)</gadget>
<output>210</output>

<result>210</result>