Question 668983
Let w be the width. You are told the length, l, is {{{w+3}}}
You know the area of a rectangle is given by {{{Area = length * width}}}
Plug in
{{{Area = length * width}}}
{{{54 = (w+3) * w}}}
{{{54 = w^2 + 3w}}}
{{{0 = w^2 + 3w - 54}}}
{{{0 = (w +9)(w-6)}}}
So w must be either -9 or 6
Since the width can;t be negative, it must be 6 feet.
That makes the length 6+3 = 9 feet.