Question 188867
Let L = length of the rectangle
    L-2 = width of the rectangle
    
The perimeter of the rectangle is 2*width + 2*length

{{{((2*L)+(2*(L-2)))=80}}}

Simplifying...

{{{(2*L)+(2*L)-4=80}}}

{{{(4*L)-4=80}}}

Add 4 on both sides

{{{(4*L)=84}}}

Divide both sides by 4 and solve for L

{{{L=21}}}

width = L-2
      = 21-2
width = 19

Length 21, Width 19