A cube has 6 sides, but you only need to find 5 of the sides since the top would be covered by the pyramid.
12(12)=144
144(5)=720
The surface area for the cube is 720 in.^2
Since the sides of the pyramid would also be 12 inches ( cause of the cube below), you would multiply the slant height with the side. There are 4 sides. The base will not matter because it is covered by the cube.
10(12)=120
120(4)=480
The surface area of the pyramid would be 480in.^2
720 + 480 = 1200
The total surface area of the figure is 1200in.^2