Ding Ding reads a book, if he reads 15 pages a day on average, he can finish it in 12 days, but he actually reads it 2 days ahead of time, how many pages does he read on average every day?
小丁丁看一本书，如果平均每天看15页，12天可以看完，实际提前2天看完，实际平均每天看多少页？
<gadget id="calculator">180 / 10</gadget>
<output>18</output>

<result>18</result>