Divide a cube into two cuboids with unequal volumes. The volume of the small cuboid is (4/5) the volume of the large cuboid, and the volume of the large cuboid is 15dm**3. What is the length of the sides of the cube in dm
将一个正方体分成体积不相等的两块长方体，小长方体的体积是大长方体体积的(4/5)，大长方体的体积是15dm**3，那么正方体棱长是多少dm
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