Answer:
a)

b) 216 cm^2
Explanation:
A) the area of one face of the cube, is the side length x the side length. As it is a cube, all sides are the same length, so we do c x c =

There are 6 faces in a cube so we have to times one face by 6 to get

B) c = 6
substituting this into the equation we made:
6 x (6)^2
6 x 36
216
So the surface area is 216 cm^2.
Hope this helps, let me know if you have any questions :)