Xiao Ming reads a book. I read the whole book (1/4) on the first day, and 135 pages on the second day, leaving 30%. How many pages does this book have?
小明看一本书．第一天看了全书的(1/4)，第二天看了135页，还剩下30%．这本书一共有多少页？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">30 / 100</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (1/4) - (3/10)</gadget>
<output>9/20 = around 0.45</output>

<gadget id="calculator">135 / (9/20)</gadget>
<output>300</output>

<result>300</result>