The sum of the side lengths of a cuboid and a cube is equal. Given that the length of the cuboid is 5 cm, the width is 3 cm, and the height is 4 cm, find the side length of the cube.
一个长方体和一个正方体的棱长之和相等，已知长方体的长为5厘米，宽为3厘米，高为4厘米，求正方体的棱长．
<gadget id="calculator">5 + 3 + 4</gadget>
<output>12</output>

<gadget id="calculator">4 / 12</gadget>
<output>1/3 = around 0.333333</output>

<gadget id="calculator">12 * (1/3)</gadget>
<output>4</output>

<result>4</result>