Let x ft be the lenght of the fence and y ft be the width of the fence.
1. The length of the habitat should be at least 80 feet, then
[tex]x\ge 80\ ft.[/tex]
2. The perimeter of the habitat should be no more than 300 feet. The perimeter of the fenceis 2x+2y ft, then
[tex]2x+2y\le 300\ ft.[/tex]
3. The system of inequalities that represent the model is
[tex]\left\{\begin{array}{l}x\ge 80\\2x+2y\le 300\end{array}\right..[/tex]
The graph of these inequalities is attached.
Two possible solutions are