Step-by-step explanation:
So for this question just substitute the value and work out. I thought it it to the power of 2 as I can't tell from the question.
Where's the system? I can't answer your question without it.
2(4*8) + 2(12*4) + 2(12*8)
= 352 cm^2
I took every face alone (6 in total) and multiplied Length by width. You have two from every face.
The range is 18. Hope this helps!