There are 46 books on the first floor of the bookshelf, 70 books on the second and third floors, and 52 books on the fourth floor. How many books are placed on each floor on average?
书架上第一层放46本书，第二层和第三层共放70本书，第四层放52本书，平均每层放了多少本书．
<gadget id="calculator">46 + 70 + 52</gadget>
<output>168</output>

<gadget id="calculator">168 / 4</gadget>
<output>42</output>

<result>42</result>