Answer:
1356 cm²
Step-by-step explanation:
Each dimension gets multiplied by 2, so the new dimensions are
changed from 2x8x7 to 6x24x21
There are 6 faces to the prism,
The area of the front and back are 6x21 = 126. There are 2 of them for a total area of 126x2 = 252 cm²
The are of the left and right sides are 24x21 = 504. There are 2 of them for a total area of 504x2 = 1008 cm²
The area of the top and bottom are 6x24 = 144, there are 2 of them for a total area of 144x2 = 288 cm²
The total surface area is 252 + 1008 + 96 = 1356 cm²
