Answer:
6(5 x 5) + 6(3 x 3) - 2( 3 x 3)
Explanation:
Each side of the bigger cube is 5 x 5 and there's 6 sides 6(5 x 5)
Each side of the smaller cube is 3 x 3 and there's 6 sides 6(3 x 3)
We need to deduct the overlapping space which is equivalent is 3 x 3 and we calculated it twice so 2(3 x 3)