Lele reads a 264-page story book. She reads an average of 19 pages a day in the first 3 days, and reads it in the remaining 9 days. How many pages a day does she read on average?
乐乐看一本264页的故事书，前3天平均每天看19页，剩下的9天看完，平均每天看多少页？
<gadget id="calculator">3 * 19</gadget>
<output>57</output>

<gadget id="calculator">264 - 57</gadget>
<output>207</output>

<gadget id="calculator">207 / 9</gadget>
<output>23</output>

<result>23</result>