Question 956109
L=length;W=width; P=perimeter=68ft; A=area=288 sq ft
A=L*W
L=A/W
P=2(L+W) Substitute for L
68ft=2((A/W)+W) Divide each side by 2
34ft=(288sqft/W)+W Subtract W from each side.
34ft-W=288sqft/W Multiply each side by W
{{{-W^2+34W=288}}} Subtract 288 from each side.
{{{-W^2+34W-288=0}}}*[invoke quadratic "W", -1, 34, -288 ]
The width is 16ft or 18ft and length is the other.
ANSWER: The dimensions are 18 feet by 16 feet.
CHECK: 
P=2(L+W)
68ft=2(18ft+16ft)
68ft=2(34ft)
68ft=68ft
A=LW
288 sq ft=(18ft)(16ft)
288 sq ft=288 sq ft