The older brother and the younger brother read the same book. The older brother finished it in 8 days, and the younger brother finished it in 10 days. The younger brother read 3 pages less than the older brother every day. How many pages in this book are there?
哥哥和弟弟看同样一本书，哥哥8天看完，弟弟10天看完，弟弟比哥哥每天少看3页，这本书共有多少页？
<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">3 / (1/40)</gadget>
<output>120</output>

<result>120</result>