A fairy tale has 138 pages, Li Ming has already read 66 pages, and he plans to finish the rest in 4 days, how many pages per day on average?
一本童话故事有138页，李明已经看了66页，剩下的他打算4天看完，剩下的平均每天看多少页？
<gadget id="calculator">138 - 66</gadget>
<output>72</output>

<gadget id="calculator">72 / 4</gadget>
<output>18</output>

<result>18</result>