Answer:
531 in²
Step-by-step explanation:
5 faces of the cube are facing the surface because the top one is shared with the triangular prism.
Surface area of a cube is S = 5 × (9)²
S = 405 in²
Now the triangular prism: S = (1/2)lP + B, where l is slant height and p is the perimeter of the base. (ignore B base area because this is also not facing the surface/shared with the cube).
S = (1/2)7×(4×9)
S = 126 in²
Add 126 + 405 to get 531 in²
