Explanation:
so, let me get this straight :
s = sqrt(sa/6)
this is because the surface area of a cube consists of 6 squares (as everybody knows that dice have 6 equal sides).
and the area of a single square is side².
for a cube with sa = 180 m² we have
s = sqrt(180/6) = sqrt(30)
for a cube with sa = 120 m² we have
s = sqrt(120/6) = sqrt(20) = sqrt(4×5) = 2×sqrt(5)
so, the side length of the larger cube is
sqrt(30) - 2×sqrt(5) meters
longer than the side length of the smaller cube.
in other words, the difference between both side lengths.