[tex]x-\ length\\
y-\ width\\\\
x+0.3=2y\ \ \ \ \ | subtract\ 0.3\\x=2y-0.3\\
perimeter=2x+2y\\ 2x+2y-14.4=y\\\\
2*(2y-0.3)+2y-14.4=y\\
4y-0.6+2y-14.4=y\\
6y-15=y\ \ \ | add\ 15\\
6y=15+y\ \ | subtract\ y\\
5y=15\ \ \ | divide\ by\ 5\\
y=3\\
x=2y-0.3=2*3-0.3=6-0.3=5.7\\\\
Dimensions:\ length=5.7\ feet\, width=3\ feet.[/tex]