Question 59072
in a rectangular prism there is always 2 opposite sides that have the same area,  
to find the surface area, the sides, multiply by LxW and multiply by 2.
since there are 3 sets of sides we have to make 3 calculations and add the together.

LxW is one set
LxH is another set
WxH is the third set

set 1=(2)x(8)x(5)
set 1 surface area is 80cm squared
set 2=(2)x(8)x(3)
set 2 surface area is 48cm squared
set 3=(2)x(5)x(3)
set 3 surface area is 30cm squared

to find the total surface area, add the numbers together.

the total surface area of the cube is 158cm squared