There are two layers of books on the bookshelf, the upper layer has 28 sets, 8 sets of the same books are less than the lower layer, how many sets of books are placed in the lower layer?
书架上有上、下两层书，上层有28套，比下层少8套同样的书，下层放了多少套书？
<gadget id="calculator">28 + 8</gadget>
<output>36</output>

<result>36</result>