Answer:
3 ft
Explanation:
A cube is made of 6 equal faces each of which is a square with the same side length. The surface area of the cube is the surface area of one side multiplied by 6. We know the surface area is 54 so divide this by 6.
54/6 = 9 ft^2
Since the surface must be a square, take the square root of 9 which is 3 ft. The length of one edge of the cube is 3 ft.