A book, I read (1/3) of it on the first day, read the rest (1/2) on the second day, and there are 20 pages left, how many pages does this book have?
一本书，第一天看了它的(1/3)，第二天看了剩下的(1/2)，还剩20页没有看，这本书有多少页？
<gadget id="calculator">1 / 2</gadget>
<output>1/2 = around 0.5</output>

<gadget id="calculator">1 - (1/2)</gadget>
<output>1/2 = around 0.5</output>

<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">20 / (1/2) / (2/3)</gadget>
<output>60</output>

<result>60</result>