Answer: 158 square feet
=====================================================
Work Shown:
36 inches = 3 feet
Divide by 12 to go from inches to feet
The block has the dimensions
Use the formula below to calculate the surface area
SA = 2*(LW+LH+WH)
SA = 2*(5*8+5*3+8*3)
SA = 2*(40+15+24)
SA = 2*(79)
SA = 158 square feet
So if you had 158 square feet of wrapping paper, then you can cover this entire 3D box without any gaps or overlaps. The paper can be folded over the box, or you can cut/glue the pieces on, but make sure there isn't any leftover scraps of paper.