The bookshelf has three layers: upper, middle, and lower. The number of books on the upper layer is three times that of the middle layer, and the number of books on the lower layer is four times that of the middle layer. If 5 books are taken from the lower layer every day, then there are still 3 books left after 9 days , Find the number of books on the upper level.
书架有上、中、下三层，上层的书的本数是中层的3倍，下层书的本数是中层的4倍，如果从下层的书里每天取5本，那么9天后还剩下3本，求上层的书有多少本．
<gadget id="calculator">5 * 9</gadget>
<output>45</output>

<gadget id="calculator">45 + 3</gadget>
<output>48</output>

<gadget id="calculator">48 / 4</gadget>
<output>12</output>

<gadget id="calculator">12 * 3</gadget>
<output>36</output>

<result>36</result>