The equation for surface area of rectangular prisms is 2ab + 2bc + 2ac. The length is a the width is c and the height is b. Plug this in and solve. A=5 B=8 C=3. You should come up about with 2(5)(8) +2(8)(3) + 2(5)(3). This will equal 80 + 48 + 30 = 158 That is your answer.