perimeter of the rectangle = 136 feet
let
width = w
l = length
Therefore,
[tex]\begin{gathered} l=3w \\ \text{perimeter = 136 ft} \end{gathered}[/tex][tex]\begin{gathered} \text{perimeter of a rectangle=2(l+w)} \\ 136=2(3w+w) \\ 136=2(4w) \\ 136=8w \\ w=\frac{136}{8} \\ w=17ft \end{gathered}[/tex][tex]\begin{gathered} l=3w \\ l=3\times17 \\ l=51ft \end{gathered}[/tex]width = 17 feet
length = 51 feet
