A book, after reading (1/3) of it and then reading 30 pages, only 60% of it is left. How many pages does this book have?
一本书，读完它的(1/3)后再读30页就剩下它的60%，这本书一共有多少页？
<gadget id="calculator">60 / 100</gadget>
<output>3/5 = around 0.6</output>

<gadget id="calculator">1 - (3/5)</gadget>
<output>2/5 = around 0.4</output>

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

<gadget id="calculator">(2/5) - (1/3)</gadget>
<output>1/15 = around 0.066667</output>

<gadget id="calculator">30 / (1/15)</gadget>
<output>450</output>

<result>450</result>