OK so I have looked this up and still have yet to figure out remotely even how to do this problem

problem: A=2(wl+wh+lh) solve for w (surface area of a rectangular box)

A box has 3 dimensions

Height
Length
Width

If Height = 4, Length = 5 and Width = 3, then use that to complete your own formula:

A=2(wl+wh+lh)
A=2((3*5) + (3*4) + (5*4))
A=2(15+12+20)
A=2(47)
A=94

Now that you understand the process, you can figure out any one of the dimensions if you know the other 3, If you know AREA & WIDTH & LENGTH, you can use algebra to work backwards and figure out the HEIGHT.

p=2(l+w)