When Xiaoliang reads a book, he originally planned to read 20 pages a day, and he can finish it in 12 days. In fact, he reads 4 more pages a day. According to this calculation, how many days can he finish it in advance?
小亮看一本书，原计划每天看20页，12天可以看完，实际每天多看4页，照这样计算，可以提前几天看完？
<gadget id="calculator">20 * 12</gadget>
<output>240</output>

<gadget id="calculator">20 + 4</gadget>
<output>24</output>

<gadget id="calculator">240 / 24</gadget>
<output>10</output>

<gadget id="calculator">12 - 10</gadget>
<output>2</output>

<result>2</result>