check the picture below.
so, the cube is really, just a rectangular prism, which is really just 6 rectangles stacked up to each other at the edges.
so, the area of it is just the area of those sides
top and bottom 5x5, 25 each
left and right, 5x5, 25 each
front and back, 5x5, 25 each
so the area is 50+50+50, or 150 cm²
the volume is either face, times the length, so just 25 * 5, or 125 cm³.
now, let's check their ratio. [tex]\bf \cfrac{area}{volume}\qquad 150:125\implies \cfrac{150}{125}\implies \cfrac{6}{5}[/tex]
