A bookshelf contains 126 books on the upper shelf, 157 books on the middle shelf, and 95 books on the lower shelf. Ask a mathematical problem and choose an appropriate method to solve it.
一个书架上层放126本书，中层放157本书，下层放95本书．提出一个数学问题，并选择合适的方法解决它．
<gadget id="calculator">126 + 157 + 95</gadget>
<output>378</output>

<result>378</result>