Xiao Ming reads a book. I read the whole book (1/4) for the first time, and read 30% of the whole book the next day, and there are 135 pages left. How many pages are there in total?
小明看一本书．第一看了全书的(1/4)，第二天看了全书的30%，还有135页没看，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>