A book has read (3/4) and there are 30 pages left, how many pages does this book have?
一本书看了它的(3/4)还剩30页没有看，这本书有多少页？
<gadget id="calculator">3 / 4</gadget>
<output>3/4 = around 0.75</output>

<gadget id="calculator">1 - (3/4)</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">30 / (1/4)</gadget>
<output>120</output>

<result>120</result>