Respuesta :

The formula for surface area are 2(LW+LH+WH). If the numbers were being placed in the formula, it will become 2[(9*7)+(9*12)+(12*7)]. 9*7 is 63, 9*12 is 108, 12*7 is 84 and the sum will be 255, and multiply by 2 is 510.
The answer is 510