Find the surface area of a rectangle prism

Surface area
it is 6 rectangles
rectangle area=legnth times width

but yo have legnth width and height
how does we do this?
answer
recognize that the rectanles come in pairs
rectanels that are oposite each other have equal areas
so we have
top=bottom=legnth times width
front face=back face=legnth times height
R side face and L side face=width times height

since there are 2 of each
SA=2(LW)+2(LH)+2(WH)
undistribute 2
SA=2(LW+LH+WH)

tada
(note: L=legnth, W=width, H=height)

and give your answer in square units