Question

find Area of surface of 12 meters, 5 meters, and 4 meters

Answer 1

the area will be three pairs of rectangles, of dimensions 12x5, 12x4, 5x4.
I assume you know how to find the area of a rectangle...

Answer 2

As = (L*W)*2 + (L*h)*2 + (W*h)*2
As = (12*5)*2 + (12*4)*2 + (5*4)*2 = __m^2.