First, find the surface area of the bigger sides (there are 4 of them so what you get for one you will multiply by 4)
12 x 8 = 96
96 x 4 = 384
Then find the surface area of the smaller sides ( there are two small sides so multiply your answer by two)
8 x 8 = 64
64 x 2 =128
Then add both together
128 +384 = 512
Hope this helps :)
