Let the side of the second cube be x, then the side of the second cube is 2x.
Volume of a cube = s^3
x^3 + (2x)^3 = 72
x^3 + 8x^3 = 72
9x^3 = 72
x^3 = 72/9 = 8
x = cube root (8) = 2
Therefore, the side length of the first cube is 2x = 2(2) = 4cm
while the second cube is 2 cm long.
