If it is 2d it is 126
It has 4 sides 2 of them are 12 so add them up and you get 24
And 276-24=252that leaves to more side so divide that 252 by
2 and you get 126
If it is 3d it is 28.5 or 28 1/2
12×4=48
276-48=228
228÷8=28.5 or 28 1/2
I hope I helped if I did Mark me as brainliest