Xiao Liang finished reading a book in 3 days. He read (1/5) of the whole book on the first day, 40% of the whole book on the second day, and 40 pages on the third day. How many pages does this book have?
小亮3天看完了一本书，第一天看了全书的(1/5)，第二天看了全书的40%，第三天看了40页，这本书共有多少页？
<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">1 - (1/5) - (2/5)</gadget>
<output>2/5 = around 0.4</output>

<gadget id="calculator">40 / (2/5)</gadget>
<output>100</output>

<result>100</result>