Xiao Ming reads a book, 13 pages on the first day, 17 pages on the second day, and 12 pages on the third day. How many pages does he read per day on average?
小明读一本书，第一天读了13页，第二天读了17页，第三天读了12页．他平均每天读多少页．
<gadget id="calculator">13 + 17 + 12</gadget>
<output>42</output>

<gadget id="calculator">42 / 3</gadget>
<output>14</output>

<result>14</result>