Xiao Ming intends to finish a storybook in 15 days, with an average of 12 pages per day. Now he has to finish it 3 days in advance, how many pages per day on average?
小明打算15天看完一本故事书，平均每天看12页，现在要提前3天看完，平均每天看多少页？
<gadget id="calculator">15 * 12</gadget>
<output>180</output>

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

<gadget id="calculator">180 / 12</gadget>
<output>15</output>

<result>15</result>