A book, read 12 pages on the first day, read 40% of the book on the second day, and there is still (1/3), how many pages does this book have?
一本书，第一天看了12页，第二天看了全书的40%，还剩下(1/3)，这本书有多少页？
<gadget id="calculator">40 / 100</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">1 - (2/5) - (1/3)</gadget>
<output>4/15 = around 0.266667</output>

<gadget id="calculator">12 / (4/15)</gadget>
<output>45</output>

<result>45</result>