Answer:
36 feet
Step-by-step explanation:
First, find the perimeter of the garden in grade's units. Plot the vertices on the coordinate plane (see attached diagram). The picture shows that garden is rectangular. The perimeter of the garden is
[tex]P=AB+BC+CD+AD=4+5+4+5=18\ un.[/tex]
If each grade square has a length of 2 feet, the perimeter of the garden is
[tex]P_{actual}=18\cdot 2=36\ ft.[/tex]