let n = length
let n-4 = width since it is 4 meters shorter
2( n+n-4) =72 Two of the length and width added together equal the perimeter
combine like terms
2(2n -4) = 72 Now use the distributive law on the left side of the equation
4n -8 = 72 Now add 8 to both sides
4n -8 +8 = 72 +8
4n = 80 Finally divide each side by 4
n=20
so the length is 20 and the width is 4 less or 16.
Let's see if our answer works.
20 + 16 + 20 +16 =? 72
72 =72 yes, it does. Length = 20 Width = 16
