Ding Ding reads a story book, read (2/5) of this book on the first day, and (1/4) of this book on the second day, and there are still 70 pages left, how many are there in this book? Page?
丁丁看一本故事书，第一天看了这本书的(2/5)，第二天看了这本书的(1/4)，还有70页没看，这本书一共有多少页？
<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 - (2/5) - (1/4)</gadget>
<output>7/20 = around 0.35</output>

<gadget id="calculator">70 / (7/20)</gadget>
<output>200</output>

<result>200</result>