Xiaodong reads a story book. He reads 50 pages of the whole book on the first day and 70 pages of the whole book on the second day. At this time, there are only 2/5 of the whole book left. How many pages does this storybook have?
小东看一本故事书，第一天看了全书的50页，第二天看了全书的70页，这时还剩下全书的(2/5)．这本故事书一共有多少页？
<gadget id="calculator">50 + 70</gadget>
<output>120</output>

<gadget id="calculator">2 / 5</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (2/5)</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">120 / (3/5)</gadget>
<output>200</output>

<result>200</result>