Question 689852
Let the width be w. Then the length = {{{w + 3}}}
The area of a rectangle is {{{area = length * width}}}
{{{180 = (w+3) * w}}}
{{{180 = w^2 + 3w}}}
{{{0 = w^2 + 3w - 180}}}  Now factor this or use the quadratic equation
{{{0 = (w - 12)(w+15)}}}
So either w-12= 0  or w+15=0
Thus w = 12 or w = -15

Since the width cannot be -15 feet, then the width must be 12.
Which makes the length 15.

Get it?