A book has been read (2/5), and there are 60 pages left, how many pages does this book have?
一本书已经看了(2/5)，还剩下60页没有看，这本书有多少页？
<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">60 / (3/5)</gadget>
<output>100</output>

<result>100</result>