The exercise is basiacally asking for the perimeter of the garden. The perimeter of a rectangle is twice the sum of its dimensions, so we have

Answer:
Base = 1.5 ft
Step-by-step explanation:
Area = ½ × base × height
9/16 = ½ × base × 3/4
9/16 = 3/8 × base
base = 9/16 × 8/3
base = 3/2
base = 1½ ft