Answer:
252 in²
Step-by-step explanation:
You have to calculate the area of each surface and sum all they after:
Top area: 6 × 12 = 72 in
Front area: 3 × 12 = 36 in
Side area: 6 × 3 = 18 in
You have 2 rectangles with the same measure of the top, of the side and the front, so multiply each area per 2:
72 × 2 = 144
36 × 2 = 72
18 × 2 = 36
Now you sum all the areas:
144 + 72 + 36 = 252 in²
