Xiao Ming reads a book and originally planned to finish it in 8 days, but actually read 4 pages less than the original plan every day, so he finished the book in 10 days. How many pages does this book have?
小明看一本书，原计划8天看完，实际每天比原计划少看了4页，这样用10天看完这本书．这本书一共有多少页？
<gadget id="calculator">1 / 8</gadget>
<output>1/8 = around 0.125</output>

<gadget id="calculator">1 / 10</gadget>
<output>1/10 = around 0.1</output>

<gadget id="calculator">(1/8) - (1/10)</gadget>
<output>1/40 = around 0.025</output>

<gadget id="calculator">4 / (1/40)</gadget>
<output>160</output>

<result>160</result>