Xiao Ming has a book of 180 pages, and he has read 60 pages. If the rest of the book is to be read within 4 days, how many pages will be read per day on average?
小明有一本180面的书，已经看了60页．如果剩下的部分要在4天内看完，平均每天要看多少页？
<gadget id="calculator">180 - 60</gadget>
<output>120</output>

<gadget id="calculator">120 / 4</gadget>
<output>30</output>

<result>30</result>