Little Ding Ding reads a book, originally planned to read 16 pages a day, and finished it in 15 days. In fact, he finished reading 3 days in advance. How many pages does Ding Ding actually read on average every day?
小丁丁看一本书，原计划每天看16页，15天看完．实际他提前3天就看完了，小丁丁实际平均每天看多少页？
<gadget id="calculator">15 - 3</gadget>
<output>12</output>

<gadget id="calculator">15 / 12</gadget>
<output>5/4 = around 1.25</output>

<gadget id="calculator">16 * (5/4)</gadget>
<output>20</output>

<result>20</result>