Fatty reads a story book, 12 pages a day, and he reads half of the book in 5 days. He plans to finish the remaining pages in 4 days. How many more pages must he read every day on average?
小胖看一本故事书，每天看12页，5天正好看了全书的一半，剩下的页数他打算4天里看完，他必须平均每天比原来多看几页？
<gadget id="calculator">5 / 4</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">12 * (5/4)</gadget>
<output>15</output>

<gadget id="calculator">15 - 12</gadget>
<output>3</output>

<result>3</result>