Xiao Ming reads a science fiction novel. He reads (1/4) of this book on the first day, reads more (1/5) on the second day than the first day, and reads less (1/5) on the third day than the first day 5) At this time, there are 30 pages left to read. How many pages are there in this book?
小明看一本科幻小说，第一天看了这本书的(1/4)，第二天看的比第一天多(1/5)，第三天比第一天少看(1/5)，这时还剩30页未看，这本书共有多少页？
<gadget id="calculator">1 / 4</gadget>
<output>1/4 = around 0.25</output>

<gadget id="calculator">1 / 5</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 + (1/5)</gadget>
<output>6/5 = around 1.2</output>

<gadget id="calculator">(1/4) * (6/5)</gadget>
<output>3/10 = around 0.3</output>

<gadget id="calculator">1 - (1/5)</gadget>
<output>4/5 = around 0.8</output>

<gadget id="calculator">(1/4) * (4/5)</gadget>
<output>1/5 = around 0.2</output>

<gadget id="calculator">1 - (1/4) - (3/10) - (1/5)</gadget>
<output>1/4 = around 0.25</output>

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

<result>120</result>