Read a book (2/5) on the first day, read the rest (1/3) on the second day, and read the remaining 40 pages on the third day. How many pages does this book have?
一本书第一天看了(2/5)，第二天看了余下的(1/3)，第三天看完余下的40页，这本书共有多少页？
<gadget id="calculator">1 / 3</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">1 - (1/3)</gadget>
<output>2/3 = around 0.666667</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">40 / (2/3) / (3/5)</gadget>
<output>100</output>

<result>100</result>